I think the card is fine as it is. Immaterial makes it OP and turns makes it UP imo. If anything, I would reduce the healing to 3.
Something that does need to be changed is the effect devourer and BH have when sanc. is in play. Right now Devourer does not return a
to the opponent if it attacks you, but BH does heal the opponent if used on you when no quanta is absorbed. Both skills have similar wording of "do X if quanta is absorbed", but do different things when no quanta is absorbed. Either BH needs to do no healing or Devourer needs to receive a
if sanctuary is in play.