Everyone is saying we should have a goblin hero, and when that happens, they are just going to ask for a giant hero, so what about a minion hero? At level 5 it unlocks its' special ability: Dark spray, where it shoots a big splatter of dark elixir, that Damages buildings, and acts like a freeze spell.
The paralyse effect would be too OP as the hero could immobilize the target endlessly - How about it does very little damage but weakens defenses' DPS and does NOT stack.