Fire

Fire or Flames refers to the special particles produced by the Pyro primary weapons. When these particles connect to an enemy player, a damage-over-time affect (sometimes called a DOT) called afterburn. Fire has its own damage type, and some other weapons which aren't Pyro primary weapons also have fire-like properties.

A Burning Spy.

Flame mechanics

When the fire button is pressed with the Flamethrower, a stream of invisible particles launch out at a speed which depends on the Pyro's own speed at the time of launch. These invisible particles are the cause why enemy players can be lit on fire despite the visual fire not making contact. When one of these fire particles make direct contact with an enemy player's hitbox, they take damage and have a visual indication of being on fire. Unlike other projectiles, fire does not stop when colliding with the environment, and instead keeps moving until the flame particles have reached their maximum lifespan.

The momentum of fire particles as stated earlier depend on the Pyro's own momentum. When a player is moving, the player's momentum is factored, meaning a Pyro walking forward while firing these particles will extend their range. Moving backwards does the same in the opposite direction, reducing the fire particle speed.

Afterburn

The Afterburn is a DOT effect cause by the stock Flamethrower and the Flare Gun. When a afterburn-causing attack lands, the target is set aflame with a visual indicator. Upon being set aflame the character on fire will scream that they are on fire, alerting nearby Medics and teammates. Setting an oponent on fire disorients targets on fire as flame effects appear on the edge of their screen. This is especially frustrating for enemy Snipers as the scoped view while on fire will move every time the Sniper takes burning damage. When a burning player calls for Medic, their Medic speech balloon will be on fire, notifying the Medic that a teammate is on fire.

Afterburn is a particularly effective Spy Checking tool, as invisibilty or disguises are not immune to afterburn. A Pyro wishing to spy-check an area can spray flames in all directions, and any Spies will be lit. Burning players give off additional effects showing a player's true allegiance. This is useful to distinguish friendly Spies who are on fire and enemy Spies.

Afterburn can be extinguished in a variety of ways. The Pyro's own Airblast can extinguish teammates, so can healthpacks which intsantly extinguish Afterburn, water in certain maps (e.g 2Fort sewers), and any source of healing can out-heal the damage Afterburn does. Any source of healing can heal a burning teammate, giving them the health to tank the Afterburn damage and survive. It is also possible that if the enemy Pyro is wielding the Harvester, killing the Harvester-wielding Pyro will extinguish all enemy players, no matter where the Afterburn originated.

Afterburn takes effect upon taking damage from a weapon that causes it. Afterburn does 3 damage per tick, or 6 damage per second. The duration of Afterburn from Flamethrowers always stays the same no matter how many fire particles make contact, lasting around 10 seconds. Same is true for the Flare Gun. This means total Afterburn damage is 60 damage, unless the burning player extinguishes themselves.

Afterburn does not crit, however it can mini-crit if the Afterburn-causing damage is mini-crit boosted or the target is marked for death.

Note that Pyros are immune to Afterburn. Afterburn will tick once, and then the Afterburn will automatically be extinguished.

The Harvester regenerates the Pyro wielding it's health, approximately 5 per tick, or 10 health per second while held out. This also charges the HEAT meter on the Harvester; when fully charged the Harvester gets 1 guarunteed Critical Hit. This Critical Hit is only used when hitting an enemy player, even if the swing missed.

Weapons that can inflict Afterburn

{main|List of weapons}}

Name	Picture	Class	Notes
Flamethrower		Pyro
Flare Gun		Pyro
Huntsman		Sniper	Hunstman arrows only cause Afterburn if they are lit, either by a friendly Pyro or with certain map elements (e.g the torches on DeGroot Keep)

Related weapons

The following weapons have interactions based on Afterburn or fire damage.

Name	Picture	Class	Notes
Harvester		Pyro	Harevster "harvests" afterburn off of both living and dead players, regenerating the Harvester wielding Pyro's health and building the HEAT meter. Harevester Pyros that are killed extinguish the entire oposing team.
Huntsman		Sniper	Hunstman arrows cause Afterburn if they are lit, either by a friendly Pyro or with certain map elements (e.g the torches on DeGroot Keep)
Invis Watch		Spy	Cloaking while on fire will half the duration of the status effect.

Related achievements

Achievement		Description
	A Burning Memory	As a Pyro, deal 1000 afterburn damage while you're dead.
	Molten Steal	Land a Flare Gun crit on an enemy that somebody else set on fire.
	Summary Execution	Decapitate all 9 classes with the Harvester. Scout Soldier Pyro Demoman Heavy Engineer Medic Sniper Spy
	Head Rush	Decapitate 3 enemies with the Harvester in a single life.
	Don't Fear the Reaper	Save 5 teammates from burning to death by killing enemy Pyros wielding the Harvester.
	No, Time to Die	As a Spy, extinguish yourself by killing a Pyro wielding the Harvester.