Morkai's Teeth Bolts

When you give a model this Relic, select one bolt weapon (see Codex: Space Marines) that model is armed with. When that model is chosen to shoot with, you can choose for that weapon to fire a Morkai’s Teeth bolt. If you do, you can only make one attack with that weapon, but if a hit is scored, that unit is marked by Morkai until the end of the turn and the attack sequence ends. Each time an attack is made against a unit that is marked by Morkai, re-roll a wound roll of 1.