Atonement Through Honour A model with this special rule doubles its attacks in the assault phase if it is locked in combat with an IC, a MC or a Vehicle, or if the combat it is in contains more enemy models than friendly ones (count all models locked in the combat, not just the ones engaged with this model).
And They Shall Know No Fear A unit that contains at least one model with this special rule automatically passes Fear and Regroup tests. When it Regroups, the unit does not make the 3" Regroup move, but can instead move, shoot (or Run) and declare charges normally in that turn. Furthermore, if a unit containing one or more models with this special rule is caught by a Sweeping Advance, they are not destroyed, but remain locked in combat instead.
Mission Tactics The Mission Tactics special rule represents the unique way in which the Deathwatch go to war. At the start of your first turn, pick one of the Mission Tactics. It will remain active for the entire battle unless you decide to change it as described below. As long as the Tactic is active, it affects all units in your army that have the Mission Tactics special rule.
Once during the battle, at the start of any turn after the first, you can choose to change the current Mission Tactic to another one. 