An Icefire Warhead is a T'au electromagnetic pulse weapon that can be incorporated into specialised missiles fired from orbiting T'au starships. Icefire Warheads are used to aid large-scale planetary assaults, and are fired directly onto battlefields.
Once they have detonated amidst the enemy, the Icefire Warhead will disable all surrounding technologies with crippling electromagnetic pulses, sometimes resulting in catastrophic consequences for the affected technology or vehicles. These warheads continue to emit their electromagnetic pulse outwards for a significant amount of time after they have detonated.
- Apocalypse Reload, pg. 68