Watch Master

You can re-roll failed Morale tests for this unit.

When this unit fires any ranged weapons from the following list, you can choose for it to fire special ammunition. If you do so, the Bolter Discipline ability does not apply when resolving their shots, but you instead choose one kind of ammunition from the table to the right and apply the corresponding modifier. 

(absolver bolt pistol, auto bolt rifle, bolt carbine, bolt pistol(and heavy), boltgun(and combi), bolt rifle twin boltgun, stalker pattern boltgun/rifle, storm bolter, hellfire extremis(boltgun profile), all master crafted bolt weapons or a guardian spear) Table: Dragonfire Bolt, Hellfire Round, Kraken Bolt, Vengeance Round