At the start of the first battle round, you can select one Vow listed below. That Vow is active for friendly ADEPTUS ASTARTES units until the end of the battle.
Abhor the Witch, Destroy the Witch
This unit's melee attacks that target a PSYKER unit:
Accept Any Challenge, No Matter the Odds
Friendly melee attacks that target a unit with a T greater than this unit's S have +1 to wound rolls.
Uphold the Honour of the Emperor
Friendly INFANTRY units have:
Restrictions: Your army can include BLACK TEMPLARS units, but it cannot include any ADEPTUS ASTARTES units drawn from any other Chapter.