Spy

Spy is generally considered the weakest class in MvM, for a number of reasons-- however, most players buy into this stereotype despite not knowing how to play Spy and what his actual weaknesses are. Spy's primary strength is his ability to do up to 938 damage per backstab to a giant thanks to the Armor Penetration upgrade, allowing him to either kill or nearly kill any standard giant in several backstabs. Furthermore, he is able to kill any non-boss or non-giant robot in a single backstab, including Samurai Demos and Steel Gauntlets. By using his sapper, he can stun any non-giant robot, allowing him to backstab them from any angle while they're stunned, and not just from behind them. However, the sapper is virtually useless against giants, with the exception of Super Scouts who are slowed down significantly by it.

Spy faces a multitude of challenges that make him significantly harder to play than other classes:

  • After being backstabbed, giant robots will turn around and focus on you until you break line of sight or reestablish your disguise for several seconds in order to break their aggro. Giants may turn around after either one or several stabs-- it's inconsistent, but can depend on whether they have another player to worry about. In order to circumvent this behavior, it is possible to circle around a giant faster than they can turn around-- this practice is called "circlestrafing" or "circlestabbing", and takes some practice to get the hang of.
  • Similarly to giants, small robots tend to turn their attention towards you when you stab one of them. However, if they are focusing on your teammates, you might have more time to stab multiple of them in a row.
  • Spy has a small health pool, and because of the expensive upgrades for his knife, it is unfeasible to purchase resistances in the early waves. He circumvents his vulnearibility with the use of the Dead Ringer, which reduces the damage of an incoming attack by 75%, as well as granting a smaller resistance to damage while the cloak is active. However, the Dead Ringer can only be activated while the cloak meter is full, and it can take a short while for it to be recharged.
  • Spy's role as a giant killer can be made redundant depending on the circumstances. A Demoman with a crit-boosted Scottish Resistance can instantly kill a giant as soon as it drops, and multiple Heavies staying close to the robots' spawn point can stop giants from ever being an issue to deal with. Spy works best when there is some distance between the front line and the robots' spawn point, to allow for enough time for Spy to cut down the giants' health.

    • As previously explained, Spy is very prone to drawing the attention of robots. When playing, it's important to always be aware of how many robots are surrounding you, and to always have a plan to dodge their attacks once you've stabbed something. The Dead Ringer is always handy for its resistances, but remember that you can always lose the attention of robots by simply breaking line of sight, so keep an eye out for corners to turn or sources of cover to hide behind. Even if you don't know how to circlestab, you can take down a giant all by yourself by simply poking its back a couple of times, hiding for a few seconds, and then finishing them off with a couple more backstabs.

    Common mistakes

  • Pouring everything into the sapper.

    • Sapping robots is, at best, Spy's secondary role. Situations in which sapping groups of small robots is substantially useful are pretty niche, and usually just consist of groups of Heavies or Steel Gauntlets. That's not to say that the sapper is useless-- but upgrading its area of effect costs about as much as a single tick of Armor Penetration, which is a significantly more important upgrade for Spy. With certain exceptions such as wave 1 of Mannslaughter, you should avoid upgrading the sapper until you're maxed out Armor Penetration and your knife's attack speed. Remember that you can still stun robots without upgrading the sapper, and this can be very useful against Samurai Demos or individual Steel Gauntlets.

  • Playing "Money Spy".

    • This one might be a bit controversial, but Spy isn't a support class, he is a damage class first and foremost. Yes, he can collect money thanks to disguises and the Dead Ringer, but Scout is still better in almost all circumstances, and more importantly Scout is crucial for being able to provide Mad Milk for the other damage classes. If you want to play Spy, politely ask your Scout to stay Scout if he's trying to switch to another class.

    Upgrade priority

    The two most crucial upgrades for playing Spy are, in order, Armor Penetration and knife swing speed. Each tick of Armor Penetration increases a backstab's damage against giants by around 180 damage, doing 750 damage with three ticks and 938 with four. It is necessary that you fully upgrade your knife's damage as soon as possible, as Spy just doesn't do any significant damage against giants with less than three ticks, considering you might only get two backstabs at a time before having to reset their aggro-- on that front, upgrading your knife's swing speed allows you to more reliably get multiple backstabs at once on a giant, but remember that full Armor Penetration comes first.

    Outside of knife upgrades, Spy's upgrade path is very circumstantial. On certain waves where Steel Gauntlets and Heavies have more presence than giants, then sapper radius and movement speed can be valuable for getting multiple kills in a row. Relevant resistances are very important once you've upgraded your knife, though remember that the Dead Ringer allows you to halve your budget for them.

    Weapons

    Primary

    Spy's primary doesn't matter. The L'Etranger is the best option because it allows you to regain your Dead Ringer cloak by shooting at a distant robot, and the Diamondback can be used to pick off some small robots. Ultimately, though, just use whatever you've got, and remember that Gun Spy is not viable.

    Secondary

    Weapon Rating Review
    Dead Ringer S+ Absolutely essential for staying alive as Spy. Simply put, without the ability to block an incoming attack, Spy would simply have no chance of surviving besides wasting money on uber canteens.
    Invis Watch / Cloak and Dagger Bad Strictly speaking, the other two watches aren't unusuable, but they just don't have the protective power of the Dead Ringer, and cloak as a stealth tool is useless because disguises will always be enough to have robots ignore you.

    Melee

    Weapon Rating Review
    Conniver's Kunai S The Kunai allows you to raise your health up to 210 after a lethal backstab, and this is useful in practically every scenario. It is true that the lower initial health pool can sometimes mess you up, but the Dead Ringer will usually solve any problems you might run into.
    The Big Earner A The Big Earner grants you a speed boost and a cloak recharge on kill, allowing you to quickly chain together a number of kills on a distracted group of small robots. Note that because it lacks the Kunai's health stealing, you will need a new plan for restoring health, whether through Health on Kill or seeking dispensers and health packs.
    Knife C The stock knife has neither the health stealing of the Kunai nor the speed boost and cloak recharge of the Big Earner, but it does have a higher initial health pool. While certainly less useful, it's still usable if you don't have any other unlocks.
    Spy-cicle Bad Having your knife melted leaves you with absolutely nothing to do for 15 seconds. Pyros are not a significant threat for Spy because the Dead Ringer can extinguish you and fire resistance upgrades are cheap.
    Your Eternal Reward Bad The YER does not work the same way in MvM as the way it does in PvP. Backstabbing a robot doesn't apply your disguise instantly, but instead has the same delay present for applying a normal disguise. In other words, the sole upside of the YER has been completely removed in MvM, and is thus useless.

    Sappers

    Both of them do the same thing.