Krak Grenades

The controlling player may choose to have a model with krak grenades that is Engaged or otherwise in base contact during the Assault phase with a Building or Fortification, or a model with the Vehicle, Dreadnought or Automata Unit Type, inflict one automatic Str 6, AP 3 Hit on the target in Initiative Step 1 instead of attacking normally. Any model in a unit that is chosen to inflict Hits using krak grenades may not otherwise attack or make use of any other special rule or item of Wargear that inflicts Hits or Wounds on a model in the same Assault phase (but may participate in Sweeping Advances as normal).