The Compression blast, also known as the air blast or airblast, is the alternate fire for all of the Pyro's primary weapons except the Phlogistinator. It is a blast of cone-shaped gas emitting from the end of the weapon. When the alternate fire button is used, (default key: ), the Pyro will use twenty ammunition (fifty ammunition with the Backburner equipped, twenty-five with the Degreaser, five with the Dragon's Fury) to push enemies away several feet. It can also deflect most projectiles and instantly extinguish burning teammates; the latter grants 20 Health to the Pyro upon doing so. Note that the compression blast cannot be triggered while underwater.
Projectiles within the area of effect are redirected so that they are launched towards the Pyro's crosshair. Deflected projectiles are essentially stopped and fired again from the Pyro's current position. This can give strange results if the crosshair is centered on very near objects and players, sometimes causing the deflected rocket to move at angles very different to the direction the player is facing. With the right timing and position, a skilled or well-positioned Pyro can deflect projectiles at any desired angle, regardless of their original path. Grenades and stickybombs that are already on a surface will roll in the direction pointed to by the cursor.
The following projectiles can be compression blasted:
- Rockets (Sentry Rockets, Energy Blasts, and Eyeballs)
- Grenades and cannonballs
- Baseballs and ornaments
- All liquid based projectiles, namely Jarate, Mad Milk, or Gas Passer
- Arrows, healing bolts, and repair claws.
- Energy Orb
Grenades and baseballs are not naturally given any additional vertical velocity when they are deflected. Aiming these deflected projectiles is more difficult, but their trajectory can be controlled by the Pyro's angle and position. They must be deflected upward in order to arc as they do when fired normally.
Deflected projectiles are considered to have been fired by the Pyro deflecting them for the purposes of friendly fire and kill awards. For example, a RED grenade will turn BLU when deflected and hurt any RED team players in the approximated area when it explodes. Keep in mind that a deflected explosive projectile can cause self-damage to the Pyro who deflected it. The only exception to these rules is the stickybomb. Although they can be pushed away, they do not change ownership. The only change to a deflected stickybomb is that if the Demoman who fired the stickybomb detonates it while within its blast radius, the Pyro will be credited for the kill. Additionally, deflected Detonator flares can still be remotely detonated by the Pyro that launched them. Deflected Jarate and Mad Milk soak enemy players and extinguish allies, and have all the attributes of normal Mad Milk and Jarate; for example, the Pyro will be given kill assists if a teammate kills an enemy under the effects of deflected Jarate. On-hit effects are applied to the Pyro that deflected it. For example, it is possible to gain the health bonus from the Black Box's rocket if the deflected rocket successfully hits a target. Likewise, the Crusader's Crossbow's bolts will heal teammates if deflected and the Pyro will be credited with the healing caused. Though rockets and stickybombs fired from the Rocket Jumper and Sticky Jumper respectively can be deflected, they will still not be able to do any damage.
Non-critical deflected projectiles will always turn into mini-crits, while critical projectiles retain their critical status. Additionally, a deflected baseball will only slow the player as it would for the Scout who launched it. If the Pyro is crit-boosted (for example, under the effects of the Kritzkrieg's ÜberCharge), deflected projectiles will turn into critical projectiles. Again, neither of these effects apply to stickybombs.
The deflective abilities of an air blast can be used both offensively or defensively:
- Deflecting projectiles (with the exception of the Demoman's Stickybombs) prevents them from harming teammates, even if the projectile is not relocated. This is particularly effective against grenades and rockets.
- A compression blast can be used to blow away stickybombs, making an enemy Demoman's job more difficult. This is especially useful when defending the Engineer's Sentry Gun, as stickybombs can be difficult to destroy for a single Engineer with his Shotgun or Pistol.
- An effective way to deny an enemy Über push is to use the compression blast to either push Übered players away or to separate the Medic and his patient(s).
- The compression blast can also be used to repel enemies trying to attack friendly Engineer buildings at close range. This combines well with the strong knock back of the Sentry Gun against airborne targets.
- In Control Point, King of the Hill, and Payload matches, it can be used to remove attacking players from the point in order to stave them off until teammates can get there for reinforcement.
- Airblasting an enemy carrying your Intelligence into a pit will cause your Intelligence to immediately reset.
- The compression blast can be used to increase the space between the Pyro and the enemy, allowing escape when at low health.
- Though not as effective as using flame, a compression blast will also affect cloaked Spies, which can be marginally useful as a Spy checking method if one is using the compression blast.
- In combat situations, use the surroundings to your advantage and try to blast enemies off ledges and towards other hazards on the map.
- The Medi Gun, Kritzkrieg, and Vaccinator's ÜberCharge do not prevent the knockback of a compression blast. The Pyro can take advantage of this and separate the Medic from his patient by knocking him or the patient away: This will mean that only the Medic is Übercharged and on his own.
- Invulnerable enemies can also be killed outright by compression blasting them into environmental hazards.
- Compression blasts do not affect players under a Quick-Fix ÜberCharge, including the Medic.
- The knockback from a compression blast can be used to cancel the Scout's double jump.
- The Demoman's charge can be rendered useless with the compression blast. However, one must still beware of the extended melee reach that is shared by many of the Demoman's melee weapons.
- Using the compression blast, one can juggle an enemy in the air in a predictable route, rendering them nearly helpless in the air for the Pyro or teammates to attack, or to simply advance past them.
- The compression blast can be used to force enemies into friendly Sentry Gun range for easy kills.
- The compression blast can be used to push an enemy into a corner, creating a good chance to finish them off with other weapons.
- In Control Point, King of the Hill, and Payload matches, the compression blast can be used to remove defending opponents blocking the capture, which is particularly useful when outnumbered or overpowered and the point or checkpoint has almost been captured.
- It is possible to deflect Level 3 Sentry Gun rockets back at the gun to destroy it or utilize them to kill a nearby Engineer who is repairing it.
Examples of Uses
Compression blast being used to reflect a Soldier's rocket.
Compression blast being used to push an enemy Scout off a control point.
Compression blast being used to negate an enemy uber push.
|Deflected projectiles||Kill Icon|
|Deflected Flying Guillotine|
|Deflected Sandman ball|
|Deflected Wrap Assassin ball (direct hit)|
|Deflected Wrap Assassin ball (shatter)|
|Deflected Cow Mangler 5000 energy blast|
|Deflected Cow Mangler 5000 energy blast (afterburn)|
|Deflected flare †|
|Deflected flare afterburn|
|Deflected Detonator's flare|
|Manually detonated deflected Detonator's flare|
|Deflected Detonator's flare afterburn|
|Deflected Manmelter projectile|
|Deflected Manmelter projectile (afterburn)|
|Deflected Scorch Shot|
|Deflected Scorch Shot (Afterburn)|
|Deflected grenade †|
|Deflected cannonballs (impact)|
|Deflected cannonballs (explosion)|
|Deflected stickybombs †|
|Deflected Scottish Resistance stickybombs|
|Deflected Level 3 Sentry Gun's rocket|
|Deflected Energy Orb|
|Deflected repair claws|
|Deflected Crusader's Crossbow's syringes|
|Deflected arrow †|
|Deflected arrow (Headshot)|
|Deflected flaming arrow|
|Deflected flaming arrow (afterburn)|
|Deflected MONOCULUS eye-rockets|
|Deflected projectiles||Unused Kill Icon|
|Deflected Sandman ball †|
|Deflected arrow (Headshot) †|
|Deflected flaming arrow †|
|Deflected flaming arrow (Headshot) †|
†These unused kill icons were created and contributed by NeoDement.
- As of the September 30, 2010 Mann-Conomy Update, the Pyro (through editing the items_game.txt file) has the ability to charge an airblast. Charging increases the knockback dealt to enemies. It has no effect on projectiles.
- Projectiles that can inflict afterburn get affected by Pyro's afterburn penalty from Degreaser. As result, that projectile will deal Degreaser's afterburn damage instead of the projectile's actual damage.
- Reflected grenades, Sentry Gun rockets, and Detonator flares all incorrectly inflict 85-170 self-damage (45-90 self-damage if reflected with the Dragon's Fury). 
- Reflected flares from the Scorch Shot will not inflict radius damage upon hitting a non-player surface.
- Reflected balls and baubles can only damage the Scout who shot them. While a deflected Wrap Assassin's bauble has no effect on the Scout's teammates, a deflected Sandman ball will slow them down, but still deal no damage.
- Reflected Loose Cannon cannonballs do not deal mini-crit damage.
- Even though the Pyro is credited for any kills given by a deflected Stickybomb that the Demoman detonates (including on the Demoman himself), this has no effect on the domination counter if the Demoman is not yet dominating the Pyro. However, if the Demoman is dominating the Pyro, a kill from the deflected Stickybombs will reset the counter.
- Scoring a headshot on an enemy with a deflected arrow will have the kill icon of a normal headshot (as opposed to that of an arrow headshot).
- Killed enemies with reflected rockets do not increase the killstreak counter (Does not affect Sentry Gun rockets).
- However, if the Rocket Launcher has a killstreak counter as well, it will count towards the Pyro's killstreak, but the kill feed will show the number of the Soldier's killstreak (For example, killing a Soldier with a 5 killstreak, will show as 6 killstreak on the kill feed, but will count as a single kill on the Pyro's killstreak).
- When using the airblast, enemies directly behind the Pyro may be airblasted away from him, despite them not actually being in front of the Pyro.
- If a baseball is deflected back and slows the Scout that hit it, it will show the enemy Scout assisting himself if he is killed by the Pyro.
- If a teammate kills an enemy who has recently been hit with a compression blast, the Pyro receives a kill assist.
- Strange variants of flamethrowers will not gain a kill count if an enemy is airblasted into a hazard.