Open Fire is a Power Up in the Exo Zombies map Carrier and Descent. When active, the player will have unlimited ammo. The players will have no need to reload and weapons such as launchers will become semi-automatic or fully-automatic, depending on the weapon. Also, the numbers in the ammo counter are replaced by a single infinity symbol. Some weapons that only hold one bullet in the magazine can prove especially effective while active, as there is no reload, so weapons like the RW1 and MAHEM can fire significantly faster than usual. However, the Blunderbuss and Crossbow still have to reload after every shot, although they still have the infinite reserve ammo.
Besides affecting handheld weapons, Open Fire also affects the XS1 Golitath's chain gun, rockets and homing missiles.
- Despite reloading being redundant when under the effects of this power-up, it is still possible to reload by pressing the reload button if the player did not have a full magazine in their weapon when the power-up is picked up.