Friendly fire is used to describe a situation in which a player can damage or even kill a teammate.
The ability to inflict friendly damage was originally an option available to servers during the Team Fortress 2 beta. Overall, this made setting up an ÜberCharge quicker and assisted Spies, as it discouraged Spy checking. Valve removed the feature upon release as it was known to cause errors within the game's code and harbor potential for griefing. The low focus on accurate shooting also meant that friendly fire could become an impediment if several classes attempted to cooperate with one another.
Full friendly fire is still available as a server option, but is rarely used in standard play. Because the feature has remained relatively unchanged since the beta, there are several unexpected situations that are covered below. Killing an ally will reduce the player's Kill statistic (and will go into negative numbers), but still reward a scoreboard point.
On some servers friendly fire is temporarily enabled for various reasons, such as while waiting for enough players to join, after the round ends, and during Stalemate.
In regular play
- If a Medic is healing an enemy Spy that kills a teammate or destroys a building, the Medic will receive an assist as if he were on the Spy's team.
- If a player kills an enemy who is then autobalanced to the other team, the kill feed will report the death as it were a team kill.
- It is impossible to damage or destroy an allied building.
- Certain taunts that use a weapon capable of friendly fire, including Kamikaze, Hadouken, and Fencing, can damage all allies in the area of the taunt. However, others do not, such as Skewer or Spinal Tap.
- Critical hits and mini-crits are still in effect. Most weapons which have special conditions to crit, such as the Ambassador or Bushwacka, will also continue to work properly.
- Mad Milk will not affect teammates negatively.
- The Flying Guillotine will not damage allies.
- The Sandman's ball will not damage or slow allies.
- The Fan O'War will not mark allies for death.
- The Wrap Assassin's bauble will damage teammates but not apply bleed.
- For about the first 128 Hammer Units of their flight, Rockets will pass through allies but deal splash damage from the resulting explosions.
- The Righteous Bison, which uses bundles of flame particles to simulate projectiles, does not damage teammates.
- The Mantreads will not damage teammates.
- Flamethrowers will not ignite or damage teammates.
- Airblasting a burning ally will extinguish them and give the Pyro 20 health, however no knockback is resulted from airblasting a teammate.
- For about the first 300 Hammer Units of their flight, flares from the Flare Gun, Detonator, and Scorch Shot will pass through burning teammates, but the Detonator and Scorch Shot will deal splash damage from the resulting explosions and still set teammates on fire.
- The Manmelter will not ignite or damage teammates.
- The Hot Hand will not provide the speed boost on hit when slapping a team mate.
- For about the first 128 Hammer Units of their flight, Grenades and Stickybombs will pass through allies but deal splash damage from the resulting explosions.
- The Chargin' Targe, Splendid Screen, and Tide Turner will cause the Demoman to pass straight through allies. However, if the ally is up against a wall and the Demoman charges at them perpendicularly to the wall, damage will be dealt and the resulting 'cheer' sound effect will play.
- The Ullapool Caber will deal melee damage to allies but will not explode on hitting an ally.
- The Loose Cannon does not damage teammates on collision, and Double-Donking cannot occur as a result of this.
- The Huo-Long Heater's fire ring will not ignite or damage teammates.
- The Holiday Punch will not damage teammates from behind as per norm, however will not force them to laugh.
- For about the first 300 Hammer Units of their flight, level 3 Sentry Gun rockets will pass through teammates but deal splash damage from the resulting explosions.
- The Pomson 6000 does not drain Ubercharge or Cloak from friendly Medics or Spies.
- The Short Circuit's primary fire attack will damage teammates, but its alt-fire attack will not.
- The Widowmaker does not re-gain metal on hitting a friendly player.
- The Gunslinger's three-hit-combo does not affect teammates if the former two hits were on teammates. However, hitting an enemy twice will lead to third hit dealing a crit to a teammate.
- Sentry Guns will not target teammates, and will not lock onto them if aimed at using the Wrangler.
- Teammates cannot be telefragged.
- The Crusader's Crossbow will heal teammates, rather than hurt them.
- The Ubersaw will not build uber upon hurting a teammate.
- The Blutsauger will not heal the Medic using it on hitting an ally.
- Most primary weapons will not damage teammates. However, a fully-charged Machina shot will deal damage, as well as dealing penetrating damage to teammates.
- Jarate will not affect teammates negatively.
- It is impossible to backstab teammates or sap allied buildings.