Team Fortress 2 Team Fortress 2 - Comprehensive Medic Guide (Mann vs. Machine)

This is a comprehensive guide to playing as Medic in Mann vs. Machine mode that is usable by beginners. Medic acts as a defensive backbone of the whole team, and on top of that, he can boost his allies' damage output, making him a versatile support class.

Mann vs. Machine, despite its lack of updates from Valve and notorious Mann Up mode playerbase, can be fun to play. If you want a break from standard casual play (aimbot Australian deranged gunmen included) or community deathmatch servers, give MvM a try. The beauty of Medic (and Engineer) is that as support-oriented classes, you can excel at them without having to be super skilled at the shooter part of first-person shooter.

Intro

Team Fortress 2 - Comprehensive Medic Guide (Mann vs. Machine) image 4

Like Engineer, Medic is a valued support class in Mann vs. Machine. A good Medic has the potential to help an under-performing team get through missions. Specifically, Medic helps Boot Camp MvM players in one area they often struggle with: surviving. However, I’ve found that if your teammates are below even a minimal level of competence (basically very new players), they’ll still struggle even with a Medic, and in those scenarios, you might be better off picking a class that can fight directly to pick up the slack.

In addition to the healing and overhealing Medic normally provides, he has a few abilities unique to MvM. He can project a shield that blocks most incoming attacks, and damages and slows robots it touches. He can revive recently killed teammates via Reanimators, getting them back in the action faster than if they had to wait to respawn normally. He can also share the effects of his canteens with one teammate at a time via Canteen Specialist. Medic isn’t quite as important as Engineer in my opinion but will work on most teams, especially one that don’t do a good job of staying alive. I’ve heard he’s not meta in the Expert missions and certain Advanced missions because his own damage output (not enhancing his teammates’) is low. If you ever play those missions in Mann Up, be aware some players might get (gratuitously) angry at you if you play Medic.

Medic works best with power classes (Soldier, Pyro, Heavy, Demoman), as they see the brunt of frontline combat and benefit from him the most. If the team composition is lacking power classes (i.e., a Scout, an Engineer, a Spy and a Sniper), you might be better off picking a power class. Unlike Engineer, having more than one Medic is never really a good idea, because Medic’s DPS potential independent of his teammates is the lowest of any class, and DPS is highly important in MvM. If someone else is playing Medic, either pick a different class or convince them to switch.

I want to credit the Official TF2 Wiki for a lot of information on Medic and Mann vs. Machine mechanics they provide. Without it, I couldn't have made this guide. Also, I have an MvM guide for Engineer as well, so if you like this guide, check out that one too. You're more likely to succeed in MvM if you know how to play multiple classes.

Primary Weapons

Compared to your secondary and melee weapons which have the “best” meta options, you’ll have a bit more freedom to pick the primary that you find the most helpful at keeping you and your teammates alive.

Regardless of what primary you pick, remember your main job is to support your team with your secondary. Unlike Engineer (Gunslinger, Eureka Effect), Medic doesn’t have any weapons that are so bad they’re effectively nothing more than handicaps in MvM, but the stock Syringe Gun is basically inferior to all three of its counterparts. This is because as Medic, you don’t use your primary that much, and the Syringe Gun offers no utility benefits, while its sidegrades do. The Blutsauger heals Medic for 3 HP each time a syringe hits, but it reduces Medic’s natural health regeneration by 2 HP per tick from 3-6 HP per second to 1-4 HP. A point in Health Regeneration or a few points in Healing Mastery effectively cancels this drawback out. It’s my preferred Medic primary for this mode because it allows me to heal a good chunk of my HP by firing a quick volley at robots. If I have to resort to fighting myself, the Blutsauger makes it more likely I’ll survive doing so. Remember, Medic cannot use his Medi Gun on himself.

The Overdose, which is my preferred primary outside of MvM, gives Medic 2% more movement speed for every 10% ÜberCharge he has, but only while it is the active weapon; it does not apply while wielding your Medi Gun or melee weapon. At full Uber, Medic will have 128% speed (due to quirky rounding) compared to his normal 107%. The extra speed doesn’t make a world of difference and can be substituted by Movement Speed upgrades if you have credits to spare, but it is nice for collecting money, fleeing from robots, reaching teammates, or intercepting the bomb. The Overdose has a 15% damage penalty compared to the stock Syringe Gun; a point-blank syringe from the former deals 10 damage compared to the latter’s 12 damage. The small damage reduction combined with the low importance of Medic’s primary for fighting make it an insignificant downside.

The Crusader’s Crossbow, considered the best Medic primary outside of MvM, functions differently than the other three, firing one syringe bolt at a time instead of possessing a large magazine of syringes. These bolts heal teammates they hit for 75-150 HP, with the amount increasing the further the Medic is from the target; it similarly has reverse falloff for enemies and will deal the most damage to distant targets. A point-blank bolt does 38, while a far shot can do up to 75. This is in stark contrast to the syringe guns, which are useless at longer ranges but deal more damage over time on close targets. Healing teammates with the Crossbow grants a small amount of charge to the ÜberCharge meter. If your aim is acceptable, it’s fine to use in MvM. Use it to heal teammates or damage robots from a safer distance, or to get burst healing at closer ranges. It also gives you a means of dealing with Sniper bots. The Crossbow cannot be used to revive dead teammates or give overheal.

Secondary Weapons (Medi Guns)

Medic’s Medi Guns are core to his gameplay both in MvM and normal game modes. This section mostly focuses on each Medi Gun’s unique attributes; important gameplay elements shared between them will be discussed later.

The Kritzkrieg is definitely the best choice of Medi Gun in this mode, so I’ll go over it first, but the others are usable, especially if your team is putting out plenty damage on their own or having trouble staying alive. The Kritzkrieg’s ÜberCharge charges 25% faster than the stock Medi Gun, and instead of granting invulnerability, gives the patient guaranteed critical hits for its duration. The Kritz’s healing and overheal qualities are otherwise identical to stock. Thus, it gives better overheal than the Quick-Fix or Vaccinator. Unlike Canteen Specialist + Crit canteens, the Kritzkrieg’s ÜberCharge costs no credits to use and gives crits for longer, and the Projectile Shield makes up for its lack of defensive benefit. Team damage output is very important in MvM, and the Kritz lets Medic be more than just a walking survival buffer to his teammates. The Kritzkrieg’s taunt heals Medic, but it takes 4 seconds and only heals a paltry 11 HP per use, so don’t bother trying to use it to actually heal yourself in combat. Though the Kritzkrieg should be your default choice, the other Medi Guns can be used if your team is struggling to survive, especially on the early waves.

The Quick-Fix has a 10% faster ÜberCharge rate than stock and a 40% faster healing rate. Its ÜberCharge, Mega-heal, applies a 300% rate healing effect for its duration to both Medic and patient and immunity to knockback and slowdown. It does not provide true invincibility or reduce incoming damage, so heavy fire, OHKO attacks such as Spy backstabs, or high enough burst damage will still kill you or your patient. This is the only way a Medic can overheal himself. Don’t wait until you or your patient are a few stray bullets away from death to pop it; it might not be enough to save you in time. Mega-heal also revives teammates very fast; faster than with a stock or Kritzkrieg ÜberCharge. Apart from using it to survive onslaughts or revive teammates, the Uber also works really well for healing multiple low-health teammates quickly. The knockback immunity helps when facing off against certain robots such as Pyro Pushers, Blast Soldiers, Mistake-a-Nature (sorry, Force-a-Nature) Scouts, and Heavies, as their high-knockback attacks can make them troublesome to fight. As a downside, the Quick-Fix only builds half as much overheal as the other Medi Guns by default; 125% of the patient’s max health as opposed to the others’ 150%. The Overheal Mastery upgrade helps offset this downside, but it will still have a level lower overheal ceiling than the other Medi Guns. The Quick-Fix also makes you mirror the blast jumps (and charges in Demo’s case) of Soldiers and Demomen, and the Thermal Thruster jumps of Pyros. You can take advantage of this to cover ground quickly, but it can be annoying due to the disorientation and fall damage it can cause you. If your team needs survivability and the Kritzkrieg isn’t cutting it, the Quick-Fix is likely your best alternative.

The Vaccinator is quite possibly the most unique Medi Gun. You can manually cycle between bullet, explosive, and fire resistance, in that order, using the reload button, and while healing a patient, the Vaccinator grants the two of you a passive 10% resistance to whichever resistance is currently selected. Rather than have one Ubercharge only usable at 100% charge, the Vaccinator’s bar is split into 4 sections and each Ubercharges uses 25%; granting up to 4 consecutive Ubercharges if at 100%. When an Uber is deployed, Medic and patient get a shield that lasts for 2.5 seconds protecting against the current damage type selected. It reduces damage from whatever the selected type is by 75% and reduces the damage multiplier of criticals and mini-crits of said type by 100% (sort of like how buildings take no extra damage from crits). Unlike other Medi Guns’ Ubers, the shield’s duration is not reduced by switching away from the patient or applying it to multiple patients. You can use multiple Ubercharges to protect a patient from more than one damage type simultaneously. The passive 10% damage resistance does not apply to Medic if you’re not currently healing anyone, but Uber can still be used without a patient to protect yourself. Additionally, the Vaccinator has a 67% faster Ubercharge build rate than the stock Medi Gun. Using an Ubercharge on a dead teammate’s Reanimator fills the bar by 90%, effectively reviving them instantly. The Vaccinator also benefits from the fact that most robots only use one weapon each, with very few exceptions. However, the Vaccinator has a number of serious shortcomings. For starters, it has a 33% slower overheal rate, making it ineffective for building overheal buffers, especially on multiple teammates. The Ubercharge build rate is reduced by 66% on overhealed teammates, which obviously does not synergize well with the previously-discussed downside or the fact that you’re trying to keep your teammates healthy and overhealed. As the resistance types are cycled manually, it takes more work to use than the other Medi Guns, and you can find yourself in a pickle if being attacked by melee-using robots or more than one type of robot at a time. Though you can use multiple charges in a short span of time, the brief duration of the Ubercharge is annoyingly inconvenient.

Finally, we have the good old stock Medi Gun. Its Ubercharge provides invincibility to you and your patient for its duration, but does not prevent knockback. Obviously, this offers more complete protection than Quick-Fix or Vaccinator Ubers, or the Projectile Shield (to a single teammate and yourself). Lethal environmental hazards—falling into a death pit or offstage cliff (Rottenburg)—still cause death while Ubercharged.

Melee Weapons

The Ubersaw is the most useful Medic primary in both other modes and MvM. It swings at a slower rate than the stock Bonesaw. However, each successful hit fills the ÜberCharge bar by 25%. Hitting disguised Spies or Tanks will not fill the bar. Hitting enemies with it while your own ÜberCharge is active and draining prolongs its duration, but remember the ÜberCharge effect is only active with your secondary weapon out. The Ubersaw’s downside is negligible, while the benefit allows you to quickly charge ÜberCharges and thus use them more often than if you were relying on healing teammates alone to fill it. The Bonesaw has no downsides but also no upsides, and therefore no utility.

The Solemn Vow lets you see an enemy’s health when your reticle is on them, but swings 10% slower than the Bonesaw. Since everyone has the ability to see giants’ and bomb carriers’ health by default, there’s really no reason to use it in MvM. The Amputator raises the Medic’s health regeneration by +3 HP per tick. This might seem like it’d pair well with the Blutsauger, but it’s not a very good choice. Like the Overdose, this effect is semi-passive and only applies when it is the active weapon, so you cannot heal teammates or shield while using it to regenerate health. The boost by itself will not be enough to keep you alive in the middle of an engagement. Worse, health regeneration can also be increased by the Healing Mastery and Health Regeneration upgrades. The Amputator’s taunt heals all allies near Medic for about 100 HP minimum over its duration, but cannot overheal. The only situation I’d ever even consider using it are when there are a lot of wounded teammates clustered at a control point or chokepoint, not in MvM where you can get a shield and enhanced healing capabilities for your Medi Gun. The Amputator only deals 52 damage per hit instead of the regular 65, which is enough of a drop to increase the number of hits to get kills (i.e. 3 hits on low-health classes instead of 2).

The Vita-Saw lets you collect “organs” each time you hit an enemy with it, similar to how an Eyelander Demoman collects heads upon getting kills. Don’t ask me how this works on robots. Each organ you have lets you conserve 15% of an ÜberCharge when you die, for a max of up to 60%, or 4 organs. However, it reduces your max health from 150 to 140. If melee attacking the robots is infeasible, Vita-Saw does nothing but make you passively weaker if you fail to collect enough organs and survive. The Ubersaw can be used to gain or regain Uber instead of only the latter like the Vita-Saw, and also has no passive downside, so the Vita-Saw is an inferior choice.

Medic Mechanics & Abilities

Here, I’ll discuss some common qualities of Medic’s Medi Guns, as well as his three abilities—Projectile Shield, Canteen Specialist, and revival—unique to MvM, as all are connected to Medi Gun usage. First, the Medi Guns heal a patient faster the longer it’s been since they’ve been injured by an enemy. They can also overheal teammates to 150% of their max health (i.e. up to 450 HP from 300 HP for a Heavy) by default, except the Quick-Fix, which only goes up to half that. A full overheal will decay in 15 seconds, regardless of class, assuming the patient does not take damage during this time. The Overheal Mastery upgrade increases the overheal limit by 25% and increases the duration by 50% (slows the decay rate) per point. Healing a patient removes the burning and bleeding statuses, and shortens the duration of Jarate and Mad Milk statuses. Medics build ÜberCharge by healing teammates. The rate of charge is reduced when healing a player at or near full overheal, as well as one being healed by a Dispenser or another Medic simultaneously. ÜberCharge builds faster when healing injured teammates. ÜberCharge builds at a greatly accelerated rate during setup time and between waves. The ÜberCharge of the Medi Gun, Quick-Fix, and Kritzkrieg last 8 seconds by default, but can be extended by an upgrade or Ubersaw hits. An ÜberCharge can be applied to multiple teammates by quickly switching between them with it active, though this shortens the duration. An ÜberCharge’s effect is only active while the Medi Gun is out, though the bar will continue to deplete if the Medic switches weapons. The Vaccinator’s Uber lasts 2.5 seconds and the charge is consumed immediately instead of “draining” like the others. The duration is not reduced by applying it to multiple teammates. Though tied with Spy for being the naturally second-fastest class, if a Medic is healing someone faster than him (usually a Scout), his speed will be increased to match theirs so long as the Medi Gun beam is attached to them.

The Medic has the ability to deploy a very handy Projectile Shield from his Medi Guns in MvM. It is obtained by an upgrade that costs 300 credits per point, up to two points. The second level doubles the shield’s damage dealt and increases its width. Despite the name, it also blocks hitscan (bullets); about the only things it can’t block from the robots are flames, melee attacks, and Pyro bot-reflected projectiles. Robots who touch the shield take steady damage and suffer from slowdown, but will still pass through it if the Medic doesn’t back up and they don’t die first. Moving the shield between a Medic bot and its patient will cut the former’s Medi Gun’s beam. You can still use the Medi Gun’s other abilities with the shield active. The shield is deployed by the Special Attack button (MOUSE3 by default), and lasts for 12 seconds. Like ÜberCharge, it is only active when the Medi Gun is out, but will continue to drain if the Medic switches away. The shield can be charged by more sources than ÜberCharge: damage dealt by a patient, healing a Reanimator, or blocking damage with a stock Medi Gun Uber. It also takes less time to charge than ÜberCharge. Simply healing teammates does charge it too, but not ones fully overhealed and not currently inflicting damage. It charges near-instantaneously during setup. Note that the shield is somewhat buggy and might not always stop projectiles, especially at point-blank. It does not damage Engineer bots’ buildings, but is still very useful for dealing with Sentries, as their high damage and knockback make them difficult to approach otherwise.

Whenever a player dies in Mann vs. Machine, they drop a device called a Reanimator. Medics can heal the Reanimator to revive the player on the spot, instead of them waiting to respawn back at the Upgrade Station. Revived players come back with full health, ammo, and metal like a normal respawn, but still lose any meter build/heads/killstreaks they had. A Medic must heal a Reanimator by half the teammate’s maximum health to revive them and thus the time varies by class; bringing back a Heavy will take longer than reviving a Soldier, for example. The Healing Mastery upgrade increases the speed at which teammates are revived, and the Quick-Fix is naturally good at revival, too. Using an ÜberCharge of any kind (Uber canteens don’t count) on a Reanimator greatly speeds up the progress, with a Quick-Fix Uber working faster than a stock or Kritzkrieg Uber, while a Vaccinator Uber immediately fills the revive bar by 90%. Note that for the Vaccinator Uber to work, the Medic must start healing the Reanimator before activating it, or it will have no effect. Each Vaccinator ÜberCharge can only be used to insta-revive one teammate. Healing a Reanimator builds shield charge, but not ÜberCharge. Players can decline being revived while a Medic is trying to bring them back; in this case, the Reanimator immediately disappears. It also despawns when the player respawns and a Medic is not currently trying to revive them where they died. If a player is revived more than three times in a wave, the time it takes to revive them increases, and does so again if they die more than nine times. This is indicated by a different, darker-colored icon over the Reanimator. Dying during setup time (including suicide) counts towards this for the upcoming wave, and it resets at the end of each wave, regardless if it was won or lost.

Finally, Canteen Specialist allows the Medic to share the effect of his Power Up Canteens with his teammates. To use it, activate the canteen while healing a teammate. The effect can only be shared with one person at a time, but the duration is unaffected if you stop healing them. It works with the Crits, Ammo Refill, and Uber canteens, but not Teleport to Spawn. Additionally, each level of Canteen Specialist reduces the cost of canteens for the Medic by 10 credits, for a minimum cost of 5 credits for Ammo Refill and Teleport to Spawn, and slightly increases the duration of the Uber and Crits canteens. You must exit and reopen the upgrade menu after buying Canteen Specialist for the discount to apply.

Upgrades

The Projectile Shield is Medic’s most important upgrade and the first level of it should always be the first thing you buy. The second level increases its width and damage dealt to the robots, letting you hold them off and protect your teammates more effectively. Apart from at least one level in the shield (though level 2 should also be one of the first things you get), Healing and Overheal Mastery are the next most important upgrades. Give Healing Mastery more priority at first, but Overheal Mastery is also important to have. Being able to more than double teammates’ health makes even careless players who don’t buy resistance upgrades hard to kill, even when you’re not glued to them. Lower its priority if using the Vaccinator, as it is just plain ineffective at building overheal to begin with. Healing Mastery does three things: it speeds up the healing and revival rates of your Medi Gun, and it slightly increases Medic’s natural health regeneration. Don’t invest in just one or the other if you can help it. Too little Healing Mastery, and it will be hard to heal players fast enough, get them to their overheal ceilings, or revive them efficiently. Forego Overheal Mastery, and teammates are likelier to die when hit by high amounts of damage in a short span of time, and after you stop healing them or die yourself.

After you have the shield and at least some investment in Healing and Overheal Mastery, you’ll want to get relevant resistances for the upcoming wave. Outside of a Quick-Fix Uber, you can’t use your Medi Gun on yourself, so this is extremely important for your own survival. I really have to stress this; your teammates can’t protect you from whole groups of enemies at a time, you can’t take advantage of Health-on-Kill upgrades like most other classes, and the Projectile Shield won’t always be available, nor will it block every single attack. Next in importance are ÜberCharge Duration and Canteen Specialist. ÜberCharge Duration adds two seconds per level to how long your ÜberCharges last, good for helping a teammate attack a giant or Tank, or reviving multiple dead teammates. I don’t think it affects the Vaccinator’s Ubers, so don’t bother getting it if that’s the Medi Gun your using.

Canteen Specialist is really good but not an absolute necessity for a Medic and his team to succeed. If you’re using the Kritzkrieg, buy either Crit or Uber Canteens depending on whether you think your team needs the damage or survivability more, but for the other Medi Guns, I would usually get Crits, so you still have a means of boosting damage. Choose carefully, as canteens cannot be refunded, unlike other upgrades, and you can only have one type at a time. I normally wouldn’t consider Ammo Refill canteens unless your team lacks an Engineer or he’s real selfish with his Dispenser placement. You have the ability to see how much of your patient’s current weapon’s clip is left, and for miniguns and flamethrowers, that effectively means their current ammo level. Use it when it becomes apparent your teammate has run dry.

If you have all this and still credits to spare, consider investing a point or two in Health Regeneration, Movement Speed, or Mad Milk Syringes. Health Regeneration is a poor choice on any other class except maybe Sniper, but it works okay with Medic since he doesn’t do that much killing and has natural health regeneration that the upgrade stacks with. Movement Speed helps you reach teammates or flee faster, and makes dodging projectiles and chasing down Sentry Busters to Ubersaw them easier. Upgrades to your actual weapons should have the lowest priority, but Mad Milk Syringes stands out. It causes syringes from the Syringe Gun, Overdose, and Blutsauger (but not the Crusader’s Crossbow) to apply a Mad Milk effect to one target at a time for up to four seconds. The healing stacks with the Blutsauger’s heal-on-hit attribute, but works for your whole team. Unlike the Scout’s Mad Milk, it will not slow affected robots.

Setup Time

Use the setup time to fully charge your ÜberCharge and shield meters. If you have a Demoman not using a shield or Sticky Jumper, you can use the Kritzkrieg to crit-boost his initial stickybomb trap for free, as the Uber can be quickly rebuilt. He may call out to you for this. Overheal your entire team, especially if you have Overheal Mastery. Unless the wave is about to start, I wouldn’t revive teammates who suicide for ♥♥♥ n' giggles, as there’s a revival speed penalty if teammates die too many times. Also, people suicide at the end of waves to return to spawn immediately; don't try reviving them either. Lastly, please, PLEASE remember to hit F4 once all your preparations are complete during setup. If you're using a keyboard with an fn key like I am, you might have to hold fn and then press F4. People in Mann Up are especially touchy about this.

During Waves

Heal anyone who needs it and spread your healing around the entire team, but prioritize injured teammates and frontline power classes, as they need it the most. Competent Scouts typically don’t need your healing too often, as they get healed and overhealed by collecting money. However, if your Scout currently doesn’t have overheal, give it to him. You should make an effort to not be separated from your teammates for extended periods of time, as they’re going to need your help and you aren’t well-suited for lone combat. A Medic without teammates is like an Engineer without buildings.

One of the most important things as a Medic is to keep yourself alive; you can’t heal yourself via Medi Gun outside of a Quick-Fix Uber. You do have tools to help you survive though: the Blutsauger, Mad Milk Syringes, Uber Canteens, Quick-Fix/Medi Gun/Vaccinator Ubers, and most importantly, the Projectile Shield. If injured, try to get health back via your primary, or flee to a health pack or the Dispenser. As Medic, you should have priority over your teammates when it comes to health packs. If you must abandon a teammate to keep yourself alive, especially one that is either overhealed, likely about to die themselves, or overextending, sometimes you just have to do so. Heavies can and should periodically share food with you, but this requires them to turn their attention away from the robots for a few seconds. When healing teammates and not currently shielding, try to stand as far away from them as you can so you don’t get hit by attacks meant for them, particularly fire and explosions. However, in the case of hitscan (bullets), you can crouch behind them and basically try using them as a meat shield. You don’t have to face teammates to continue healing them, so you keep an eye on your flank. You’ll want to do this when Spy bots spawn, as your teammates will likely be preoccupied with the other robots. Take care not to unwittingly heal Spies. The shield is a good way of dealing with them.

Save the Kritzkrieg’s ÜberCharge and Crit canteens for high value targets—most commonly giants and Tanks. For Tanks, don’t crit-boost Heavies, as Tanks resist their miniguns by 75%. If it is safe to do so, pull out your own weapon and attack the Tank right after using a Crit canteen to get the most out of it. Obviously, don’t use a crit canteen on a teammate who just activated one of their own; wait for it to wear off after five seconds. For the other Medi Guns’ Ubers or Uber Canteens, use them to keep yourself and/or a teammate alive. They also work well if your shield is not yet ready or is about to wear off when facing off against a dangerous giant or swarm. All ÜberCharges can be used for rapidly reviving dead teammates, and you should consider using it if multiple teammates die at once or you need someone back quickly. However, if a teammate’s Reanimator is in too dangerous a spot (such as behind robot lines) or there are other living teammates that need your help, you shouldn’t risk reviving them, especially if it will get you killed or they will likely die again right after being revived. If you die while working on the Reanimator, that’s two just dead people instead of one. Activating the shield is a good way to protect yourself and the teammate when attempting a revival.

The shield is best used defensively against giants and groups, and to keep yourself alive of course, but can be used offensively, so long as you don’t get overly aggressive. When fully upgraded, it can make quick work of many normal-sized robots, especially Scouts and Demoknights. The slowing effect is also good against giant Scouts, but your team should probably have a Scout, Sniper, or Spy slow them down properly. Position the shield between the robots and your team, and try not to turn away from the former. Apart from protecting teammates and yourself, the shield is also useful for protecting your Engineer’s Sentry if it’s under fire. Attacks can still pass through the shield if it’s too close to the robots. Simply back up as the robot(s) gets closer. Remember that the shield does not block flames. While the shield does not damage enemy Engineer bots’ buildings (I think), it lets your teammates easily get close enough to destroy their Sentries; otherwise, the Sentries' heavy firepower and knockback make it nearly impossible for anyone except Spies to approach.

You can use the Ubersaw to get ÜberCharge back up quickly and thus pop more liberally, but don’t risk your own life to do this. In general, don’t charge robots to Ubersaw them unless your teammates aren’t in danger at the moment and you have the appropriate resistances. Sentry Busters are a good source to farm Uber off of if you can catch up to them, just don’t be near them when they explode. The shield does not protect against Sentry Buster explosions.

Truncated Version

Medic is a handy support class for most MvM missions. He mainly acts as a survival buffer for his team, being able to heal, overheal, revive, and shield teammates with his Medi Guns. However, he can also boost their damage output via the Kritzkrieg or sharing crit canteens with Canteen Specialist. Medic works best with multiple power classes (Soldier, Pyro, Demoman, and Heavy), as they get the most out of Medic’s help. As a dedicated support class, Medic has very low damage output by himself and is reliant on his teammates to do most of the fighting.
Your primary and melee weapons will not be used nearly as much as your secondary, and thus are not terribly important by comparison. The default Syringe Gun has no downsides but also no utility outside of upgrading it with Mad Milk. The Overdose boosts Medic’s speed when out based on how much ÜberCharge he has, at the cost of a small damage penalty. The Blutsauger heals Medic each time a syringe hits an enemy, but lowers his passive health regeneration. The Crusader’s Crossbow fires individual syringes that heal teammates and damage enemies more the further away Medic is from them. Personally, I would recommend the Blutsauger or Crossbow.
Your secondary weapon, or Medi Gun, is central to your playstyle. The Kritzkrieg should be your default choice most of the time, as the ÜberCharge’s damage boost is fantastic, and upgrades (namely the shield) can compensate for its lack of defensive benefit. Go with the other Medi Guns only if your team is having trouble staying alive, you don’t have the Kritzkrieg, or there’s a dearth of giants/Tanks in the upcoming wave. The Quick-Fix is likely your best alternative, with a naturally faster healing and revival rate. Its Uber gives massive healing to Medic and patient for its duration, as well as knockback immunity, but it is not true invincibility. It has a lower overheal ceiling, but Overheal Mastery can compensate for this. The Vaccinator grants minor passive resistance to one damage type at a time and can be manually toggled. The ÜberCharge is split into four smaller ÜberCharges, each one giving Medic and patient 75% resistance and full crit resistance to the current damage type selected, but only for 2.5 seconds. The Uber also instantly revives dead teammates, but only one per charge. Though it charges faster than the other Medi Guns, the Vaccinator overheals very slowly and has a reduced ÜberCharge rate on overhealed patients, making it ineffective for building overheal buffers. The stock Medi Gun’s Uber grants full damage immunity for its duration, but you and your patient are still affected by knockback. It offers the most complete protection when fighting against dangerous enemies, especially if your shield is not available.
The Ubersaw should be your melee weapon of choice, assuming you have it. At the cost of slightly slower swing speed, each hit gives you 25% to your ÜberCharge meter, letting you recharge it quickly and use it more liberally. If your Uber is active and draining, successful hits with the Ubersaw prolong its duration. The Bonesaw has no utility, the Amputator deals less damage and its special abilities are of little use, and the Vita-Saw lowers your max health and is inferior to the Ubersaw.
The Projectile Shield blocks all attacks except flames, Pyro-reflected projectiles, and melee attacks. Robots who touch it take damage and slowdown, but can still walk through it. Upgrading the shield to level 2 increases its width and damage dealt. Players who die drop Reanimators, which Medic can heal to revive them on the spot. The revival time depends on the class’s max health, and there is also a penalty if they die too many times during a wave (including setup). Players can decline being revived. Healing a Reanimator with any ÜberCharge active greatly speeds up the process. For the Vaccinator, you must start healing it before using the charge. Canteen Specialist lets you share the effects of canteens with one teammate at a time. It also increases the effect’s duration, and reduces the cost of canteens for the Medic, though you must close and reopen the upgrade menu after buying Canteen Specialist first. Simply activate the canteen while healing a teammate. It cannot be distributed to multiple teammates like ÜberCharge, but the effect’s duration is not reduced if you stop healing that person after activating it.
The most important upgrade is level 1 of the Projectile Shield, due to how useful it is. Level 2 is also high-priority. After at least one point in the shield, Healing and Overheal Mastery are the next-most important upgrades. Give Healing Mastery a little more priority at first, but both are important and you should balance your credits between them. Next, you’ll want relevant resistances for yourself, as they are important for staying alive. Then, get Canteen Specialist and Uber Duration. If you get Canteen Specialist, make sure you buy Uber or Crit canteens to go with it. Crit canteens are very useful and give you a means of boosting damage even if not using the Kritzkrieg, but Uber canteens can be used for extra protection in a pinch. You can only have one canteen type at a time, and they are not refundable, unlike other upgrades. Only consider getting Ammo Refill canteens if your team lacks an Engineer and they’re having real trouble with ammo management. If you don’t have a lot of credits to spare, one point in Canteen Specialist will suffice. The Uber Duration upgrade is better than the Ubercharge rate upgrade, as the latter is expensive and can usually be substituted by opportunistic use of the Ubersaw. After Medi Gun and resistance upgrades, I recommend a little investment in Movement Speed and Health Regeneration. Upgrades for your primary and melee weapons should have lowest priority, but there is one worth mentioning: Mad Milk Syringes. This upgrade for the Syringe Gun, Overdose, and Blutsauger causes them to apply a Mad Milk effect to one robot at a time for a few seconds.
Your ÜberCharge and shield meters charge quickly during setup and between waves, so have them ready before each wave starts. If you have a Demoman using stickybombs, you can crit-boost his initial trap(s) and quickly recharge afterwards. He may call out to you for this. Overheal your entire team shortly before the wave starts.
Spread your healing around, but prioritize wounded teammates and power classes, as they need it the most. A Scout who collects money won’t need your healing as much, but you should still heal him if he needs it. Power classes are also the ones you’ll want to use ÜberCharges and canteens on. Don’t try to Battle Medic; let your teammates do most of the fighting. Don’t stand too close to your teammates so as to be less likely to get hurt by attacks directed at them, especially fire and explosives. Use the shield to protect your team during faceoffs with giants and groups of robots. As the robots get closer, back up and try to avoid turning away from them. Use Kritzkrieg Ubers and crit canteens primarily on giants and Tanks. The shield can also be used offensively, especially against weaker robots like Scouts, but don’t put yourself at risk of dying. Having resistances will make attacking with the shield and Ubersaw safer for you. For the other Medi Guns, use the Ubers to keep you and your patients alive. They are best saved for when your shield is about to run out, or will not be ready in time. ÜberCharges can also be used to quickly revive dead teammates, and consider using them for this purpose if you need someone back quickly or multiple teammates are dead. Activating the shield is a good way to protect you and the teammate during a revival attempt. You don’t always have to revive dead teammates; if it is too dangerous for you, would take too long, they are likely to die again right after being revived or there are living teammates who need your immediate help, then you probably shouldn’t try.

Source: https://gameplay.tips/guides/9262-team-fortress-2.html

Team Fortress 2 - Comprehensive Medic Guide (Mann vs. Machine)