Ranged dark elixir troop? Or support troop.
The dark barracks needs a ranged unit. Yes witches are ranged but they are also ground with their summoning. Why not make a "centaur". 5 slots like a hog rider make the Hit points and damage same cost the same. But give them the range of archers. Possibly ingore walls. But then lower damage output.
As for a support troop, I like the idea of a flying demon giving a damage boost to troops. A rage spell effect would be too overwhelming but say a 10% damage output would work. It would help mobs of weaker troops more than high damage low count.