Graviton The roll needed To Wound when firing a weapon with this special rule is always equal to the armour save of the target, to a minimum of 6+. For example, when resolving a hit against a model with a 3+ armour save, you would need a 3+ To Wound. When resolving a hit against a vehicle, roll a D6 for each hit instead of rolling for armour penetration as normal. On a 1-5 nothing happens, but on a 6, the target suffers an Immobilised result and loses a Hull Point. These weapons have no effect on buildings.