Hindrances are things that actively make things worse for your teammates. They're generally good to avoid doing.

Knockback, such as from airblast, the Force a Nature, or the Loose Cannon, may seem useful at first since it's pushing the robots away from the bomb hatch. But the goal of the game isn't to stall the robots, it's to kill them, so ultimately unless they are currently trying to do the bomb deploy animation using knockback isn't helpful. You'll be lowering both your own damage (by as high as 100% if you're using airblast instead of shooting fire) and your team's damage, by causing the robot to go further away (so they get more damage falloff instead of damage rampup) and possibly making it dodge attacks entirely. Knockback is especially annoying to Pyros, Snipers, and Spies, who will likely end up missing potentially crucial attacks and might even get killed by the robot suddenly being flung around.

Knockback Rage is so bad it gets its own little section separate from knockback. Even ignoring the fact that the upgrade costs $350 - $1,050 which could be spent on useful things, it would be terrible even if it were free and came baseline with the class. If pushing the robots away wasn't bad enough, it also cuts your damage in half. In addition to you (and your team) getting damage falloff instead of damage rampup, you just have a flat 0.5x damage multiplier while it's active.

If you're really dead set on getting this upgrade for whatever reason, save it for the bomb hatch. And don't get the second or third tier, they're useless. They have literally zero effect on grounded robots, and only affect how much airborne robots get knocked back. It's only good for sitting under where Giants drop down from so you can make them fly around in the sky, but that's just for being silly.

Also gets its own section separate from Knockback. If you separate a Medic from its patient, it will find a new patient if the patient dies. This new patient can be a Giant that already has a Medic, so it now has more. It can be another Medic, so they're healing eachother. It can be a Super Scout, so the Medic zooms across the map while healing it.

Sentry Busters have 2,500 health and explode on death*, but die immediately if they get near the Sentry they're targeting. Because of this, everyone who's played Engineer at least once knows how important it is to manipulate the Sentry Busters to get them to do what they want. If you're pushing, slowing, or otherwise messing with the Sentry Buster it will mess up the Engineer's timing and waste his time as he waits for the Buster to get where he wants it to explode. If you're killing the Sentry Buster then it's not only doing that, but also exploding in what's likely to be an inopportune place. Not to mention it prevents the Engineer from doing other things with the Buster like using it as an attack.

Unless your attacks will fill up a meter you have, like the Ubersaw, you should just ignore Sentry Busters. Just know where they are so you know where not to be when they explode, and leave them alone.

Sometimes you can't help but make robots spin around. If you're the only one who would be impacted by it, it doesn't matter, and could even be beneficial. But making robots spin for no good reason is rather bothersome. A spinning robot is safe from Pyro & Spy, likely even killing them since it's all turned around. If you think someone might benefit from the robot behaving predictably, try to avoid making it spin around whenever possible. Money doesn't need to be collected the millisecond it gets dropped, and the robot will be marked for death even if hit in the face. Getting a glass cannon teamkilled is dozens of times more impactful than marking the Giant for death (which the glass cannon won't even benefit from), so you don't even necessarily need to mark the robot if they're on it.

Also, you can cause robots to mess with Stickybombs. Explosive ones like Soldiers and Demomen are particularly prone to knocking the traps all over when spun around.

If you kill a robot in a weird far off place it's a good idea to grab the money so the Scout doesn't have to spend who knows how long looking for it. But if the money is in a place that the Scout is frequenting, picking up money is just hindering him since money can overheal him to 700 health. Even if he dies, if there's a teleporter or the map is small he probably has enough time to respawn and grab the money. But if the money is flashing it's a good idea to grab it before it burns up, assuming you can safely do it.

And no matter what, never collect the red money that Sniper creates. It's already collected and serves no purpose other than healing Scouts. If there's no Scout it's always a good idea to grab money whenever it's safe to do so.

Inefficiencies are things that lower your overall contribution, but do not hinder your teammates. Only common misconceptions that people don't understand are listed here, intentional debilitations are omit.

Unless you're Sniper or maybe Demoman, you should be pretty close to the robots. The closer you are the more damage you deal, with it capping out when you're pressing your face up against theirs. So many times I see a Brass Beast Heavy sitting so far away that I could be dealing comparable damage as Medic.

Engineer is the closest to being mandatory, but even he's optional. If you want a class so bad, you can pick that class. MvM is a lot more balanced than PvP is (other than the Valve missions and a few exceptions like Sniper being waaaay too strong), every class is great. Many times I see people pick Medic just because there's no Medic, but the rest of the team are something like Engineer (not a frontliner, Medic doesn't help much), Sniper (not a frontliner, Medic does basically nothing), Demoman (doesn't need to be close to the robots, uses cover, Medic doesn't help much), Scout (overheals himself, Medic does basically nothing), and Spy (not a frontliner, Medic doesn't help much unless exploiting robot AI which they never do).

There's nothing wrong with stacking classes. Scouts might be stealing each-other's health and Spies might get in each-other's way, but even they can work fine.

Unless the robots are on top of the bomb hatch, buying back is probably just a waste of money. Those few seconds are unlikely to be impactful in almost every single situation, but the lost money stays for the rest of the mission. Even if the robots are on top of the bomb hatch, if the waves are that close that you're needing to buyback just to not lose you probably want all the money you can have for later waves and should just try the wave again (although obviously there's no penalty to buying back at the end of the last wave, and many missions have so much money you can just spam buyback for no reason).

I have no idea why people vote to restart from wave 1 if they latejoin and see that 1 or 2 hundred dollars have been missed on wave 4/6, or complain if money got missed during a wave, but they'll spend hundreds every wave on buybacks.

Scout is tied with the Beggar's Bazooka for the second best unassisted Tank damage & best crit-boosted Tank damage, has some of the best Giant damage in the game, can easily put this damage wherever he wants due to his superior mobility, has extreme durability due to 700 overheal + tons of evasion, can do a bunch of stuff with his other weapons like Bonk! and the Sandman, and so much more.

Only picking up cash and maybe swinging the Fan or throwing Milk every once in awhile makes as much sense as an Engineer who makes a Teleporter with no other buildings, then just goes AFK.

Resistances aren't bad on Scout, but they're a lot less useful than the average class. Scout heals when he grabs money, gets up to 700 overheal by doing that, has a ton of mobility to help him dodge attacks and take safer routes, and has a bunch of weapons to help keep himself alive like Mad Milk, Bonk!, and Sandman.

Most of the time it's actually a loss of damage to mark Giants. Even if you aren't teamkilling someone by running up to the robot, and even if you aren't dying by getting so close to the robot, it's still only a 35% boost to teammates who are not being boosted by some other way (Kritzkrieg, Banner, Jarate, headshot, backstab, backburn, phlog, random crits, etc). If your team is doing enough damage to where it would be more than if you just shot the robot yourself, the robot would have died before a difference was made. If the team isn't already getting a majority of the damage getting boosted some other way and they're dealing respectable damage it can be useful against most robots that put a health bar on everyone's screen, or if there's Giants on wave 1 or 2 on missions where you're strapped for cash.

There's usually a Medic, and even when there isn't people shouldn't be relying on an overpowered vampirism to survive.

The slowdown only affects Super Scouts and small bots. Small bots should be quickly dispatched instead of slowed, and Super Scouts should meet a similar fate. Not a terrible upgrade if you're struggling against Super Scouts, but it shouldn't be bought before they arrive. And even when they do arrive there are other free ways to deal with Super Scouts, such as someone bodyblocking them (especially Heavy, Sentry, Scout, or Medic), Sandman, Rocket Specialist, Projectile Shield, Sapper, Explosive Headshot, or even Natascha.

I honestly don't even understand why people think it's so great when they also spam Crit Canteens, demand there's a Scout who does nothing but mark every single enemy for death, and demand there's a Medic who does nothing but pocket the Heavy with the Kritzkrieg. None of these stack. Again, it's not a bad weapon, it's just not the best.

It's not any better or worse than stock. The fast fire rate is offset by a damage penalty, getting damage falloff instead of damage rampup, and sacrificing a rocket to propel yourself into the air in the first place.

The Direct Hit's 25% damage does not stack with upgrades, and instead replaces one. You're essentially trading all of your AoE damage, which is what Soldier's good at, for a single $400 upgrade. If you want this playstyle I'd recommend using the Grenade Launcher, since it has 20-50% more base DPS than the Rocket Launcher while still maintaining great AoE damage. It also has no damage falloff, and can attack enemies without line of sight.

I honestly never even buy it. It's not a bad upgrade, but if you're playing well it doesn't help very much. It does three things: increase the velocity of the rockets (every tier), causes direct hits to lose damage falloff (first tier), and causes direct hits to stutter robots (first tier).

The increased velocity is more or less useless, which is why everyone tells you to only buy the first tier of it. The removal of damage falloff sounds nice, but it doesn't give you damage rampup, just removes damage falloff. Even if you're directly hitting every single rocket from far away you're only dealing 100% damage when you could be dealing up to 125% (nearly the bonus you get from minicrits) if you were actually closer, and there the upgrade wouldn't do anything. Plus, (mini)crits remove falloff, so if you're getting any of those from any of the many sources that'll also cause the upgrade to be redundant.

That leaves the only good thing the upgrade does is stuttering the robots. But it only stutters their movement, so it's only for Super Scouts. So it falls victim to the same thing the Mad Milk & Jarate upgrade do: you don't need a dedicated upgrade to stop them. Plus the stuttering makes them move in a really weird way and can cause your teammates to miss their shots.

Pyro is already the cheapest to upgrade by a huge margin, has the best unassisted Tank damage, has great crowd damage, great Giant damage, the best DPS against groups of Giants, some tricks he can use to try to take out Uber Medics, and pretty good mobility.

Don't!

They're just as good as stickies. They have some pretty good Tank damage, unlike stickybombs. Killing Uber Medics is a bit unreliable, but you can just use an unupgraded Stickybomb Launcher to take them out.

Every single time I've been Heavy with someone else also being Heavy he has the Brass Beast & terrible damage while I have the Minigun or Huo-Long Heatmaker and top damage. The downsides outweigh the upsides, unless you're doing some boring cheese that I've never seen anyone do. They always just snipe with it from really far.

You're swinging the wrench more than twice a second after upgrades, and each swing is likely to have a 60% chance to deal 195 damage and a 40% chance to deal 65. The Southern Hospitality trades that 60% chance to deal triple damage in exchange for a bleed which adds less than 4 damage per swing after upgrades, and even before a single point of attack speed it's still only adding about 6 damage per swing. And that damage doesn't apply to Tanks, and that damage doesn't change the HTK of any of the robots (like Spies), and the Southern Hospitality also makes you take more fire damage. The Southern Hospitality doesn't offer any advantages over stock, its upside is purely for PvP.

Before the super OP Projectile Shield was added everyone called Medic a troll pick. Projectile Shield is literally the only reason that Medic has been propelled into the view of the most important class. Since that's the case, why wouldn't you want to use the Medi-Gun that's by far the best at spamming Projectile Shields out, the Quick-Fix? The Shields add some pretty good AoE damage and constantly keep everyone safe. The increased heal speed and super heal Uber further the ability to keep bad teams alive. The Vaccinator basically gives people permanent invulnerability, letting them get tons of damage rampup all the time. Both are also great at reviving people.

The only Medi-Gun that might be a bit weaker than the rest is the stock Medi-Gun, but even that one's not bad.

Spy can only stab one target at a time. Maybe if there's one or two he could stab them before moving in to the Giant, but any more than that and it'd just be a lot easier for him to pop them by stabbing the patient. Stickies & Explosive Headshot are by far the best at killing Uber Medics, then comes Scout's guns & Sniper without Explosive Headshot, then comes Soldier's rockets, Demo's pills, and some things Pyro can do, then comes Spy along with basically everyone else. A Heavy with the KGB is about as good at killing Uber Medics as Spy is.

Spy's knife can easily deal over double the DPS a bodyblocking Heavy will. He should not waste his money on an expensive and subpar upgrade, nor his time on insignificant small bots. Once you are consistently killing Giants all by yourself with no help from your teammates then you can start to look at this upgrade and consider the very few situations in which it could be helpful.

And don't sap Giants. It only slows down Super Scouts, who you can simply kill in two backstabs (preferable in almost all situations). Sapping Giants doesn't do anything except make them look at you, so unless you really know what you're doing and the situation is very specific sapping Giants isn't going to do anything other than make things harder on yourself.

Overefficiencies are things that lower your teammates' overall contribution, because you are instantly completing objectives before they have a chance to even attempt to pitch in. Not everyone has a problem with these.

The most controversial of all the overefficiencies by far, some people even assume that all Pyros have Gas equipped. The Gas Passer is the most controversial for two reasons. The first is that it's by far the cheapest, lowest skill, most powerful, and most prevalent of all of them. Without Gas, Pyro is already the cheapest to upgrade by a huge margin, has the best unassisted Tank damage, has great crowd damage, great Giant damage, the best DPS against groups of Giants, some tricks he can use to try to take out Uber Medics, and pretty good mobility. Basically the only things he can't do are fight groups at a distance and reliably take out Uber Medics, both of which the Gas Passer does basically for free, in addition to the huge overall damage increase it gives.

The second is that the addition of the Gas Passer has made it so that the vast majority of people who pick Pyro do not actually have any idea how to play Pyro, and will typically throw the Gas then start doing several things from the list of hindrances before quickly dying.

Especially with the Hitman's Heatmaker. A Sniper who hits even a quarter of the shots he takes can do the mission by himself. Everyone else will be left sitting around waiting for Giants, but Sniper also has great Giant damage so they won't be able to do much against them either before Sniper kills them.

At least on Valve missions where there's about 5 hours in between bots and they hate putting more than one Giant at a time. Like with Sniper, you're just left sitting around watching Demoman right click when the bad men spawn.

Refunding is bugged. It's supposed to only be able to happen a single time per person, and you're supposed to need to earn it by collecting enough credits. Being whatever is the most overpowered for each wave is really gamebreaking.

I've seen them jokingly referred to as "bursts of skill", but I haven't seen anyone get too upset at these. They are pretty overpowered so I wouldn't be surprised if somebody did.

As I remember more misconceptions I'll add them to this guide. Let me know if you have any questions.