Team Fortress 2/Spy

The Spy is perhaps the strangest class in TF2. Though he is not effective in direct combat, he can use a combination of cloak and disguise in order to infiltrate the enemy. His knife produces an instant kill from behind and his sapper can disable and destroy buildings, making a good spy a huge asset to the team.
 * Health: 125
 * Speed: 100% (93% disguised as demoman, 80% disguised as soldier, 77% disguised as heavy)
 * Type: [[Image:TF2_achievement_with_friends_like_these.jpg||20px]] Support
 * Special Ability: Cloak

Primary Weapons

 * Revolver - Clip Size: 6 - Reserve Ammo: 24

The revolver is not really meant for heavy combat; while the rounds are more powerful than a conventional pistol, they fire slowly and come in clips of six. Use this weapon when getting away from enemies, running from Pyros, and helping your teammates kill an enemy from a distance. When facing enemy spies, it is generally advisable to switch to the revolver if you miss a backstab.

Secondary Weapons

 * Sapper - Infinite ammo

Clicking on an enemy building in melee range will plunk one of these down on it. Once it's on, a structure will be unable to perform it's function and will slowly lose HP until it is repaired or dead. An engineer can remove a sapper with 2 hits of his wrench, but you can resap immediately if you wish. A common strategy is to decloak (with a enemy disguise on) near a engineer nest, hold onto the fire button with the sapper out and run around sapping all the buildings, causing confusion and most of the time destroying a few dispensers (which could be carrying massive amounts of metal), and opening up a hole in the enemy's defense which your teammates can exploit.

Melee Weapons

 * Butterfly Knife

This weapon instantly kills if you stab from behind (and sometimes the sides). Attacking from the front, however, deals less damage than a normal melee weapon would. The most obvious situation to use the knife is for assassinating enemies, but if you're locked in close-range combat, you can whip out the knife and try to flank the enemy for an instant kill.

Using the Spy
The spy is a stealth class, first and foremost. While you can put up a fight with the revolver, your role is better filled by getting behind enemies and stabbing them in the back. Remember to decloak in the enemy's blind spot (an example would be the two corners near the two doors on each base in 2Fort), and behind the enemy is preferable as this presents a perfect opportunity for backstabs. Do not disguise as a scout (you will not gain his speed), spy (spies without masks on are spychecked frequently), or medic (you will not appear to have a ubercharge meter), or you will be spychecked frequently. Avoid bumping into enemies as this is a sure sign that you are a spy. Enemies will generally not spycheck someone coming from their side of the battlefield, presenting many backstab opportunities, but watch out for enemy sentries. Remember to avoid pyros like you would avoid a heavy as a scout, as they can set you on fire (thus breaking your cover) unintentionally. When set on fire, retreat to the nearest health kit while firing your revolver at the pyro that set you on fire. Remember that even while fully cloaked people can still see the flames. When cloaked avoid enemies.

Defeating Spies
Spies are generally very suspicious, and a few signs to watch out for are teammates on fire that glow the enemy team's color, teammates that you cannot pass through, and soap suds. A effective counter to a spy is a pyro, which can light spies up and effectively destroy their disguises and cloak. Do not melee a aware spy or you risk turning into a backstab. Spray areas that a spy has cloaked in, as cloaked spies will flicker when hit.