A Darkstar Warhead is a T'au neutron warhead incorporated into specialised missiles that can be fired from T'au starships. Darkstar Warheads are used to aid in large-scale planetary assaults, and are fired directly onto battlefields.
Once they have detonated, the neutron pulses from this warhead destroy all biological matter in an extremely large area around them, whilst leaving inorganic material unharmed.
The warhead will continue to pulse these energies outwards for a significant amount of time after they have first detonated. The Darkstar Warhead is an ideal weapon to use when it is important to conserve a target planet's resources for the Greater Good, but the home population will not submit.
- Apocalypse Reload, pg. 68