or stunned. (sorry should have added that one before)krak grenades can be used in combat against vehicles, i think theyr st6 plus 1 d6 armour penetration giving you a potential st 12 weapon, though to use these you have to sacrifice your other attacks ie you get one attempt per model per turn that has a krak grenade. also worth noting that walkers can only be hit by grenades/bombs on a to hit roll of 6 unless theyre immobilised