Press-Gang the Soul [reaction] Feat 8

Your phase cutlass steals some of the enemy's vitality, press-ganging it into eternal servitude. As long as you are wielding a phase cutlass with stolen vitality, you can cast wisp ally as a divine innate spell at will, heightened to a spell rank equal to half your level. Using wisp ally this way requires and permanently releases one soul press-ganged with your phase cutlass. The first time each round you Strike with your phase cutlass, you immediately gain the effects of the Sustain a Spell action, which you can use only to extend the duration of and control a wisp ally spell cast using that phase cutlass.