I think the idea for a "Spider" unit would be a great idea. Say his favorite target is a defensive structure and it's web slightly slows the rate of fire for that defense and maybe it can't target a new defense until that one is destroyed so maybe it'll continue to slow down that one defense until it can move to the next one. I'm thinking this will be a dark troop not only due to the spiders dark nature but because it has an effect that alters the pace of an attack to a degree that makes it more so valuable than regular elixir troops.