This was a good point. If there was one thing Gideon knew about necromancers, it was that they needed power. Thanergy—death juice—was abundant wherever things had died or were dying. Deep space was a necro’s nightmare, because nothing had ever been alive out there, so there were no big puddles of death lying around for Harrow and her ilk to suck up with a straw. The brave men and women of the Cohort looked on this limitation with compassionate amusement: never send an adept to do a soldier’s job.

Gideon the Ninth - Act One, Chapter Five