New King/queen type of troop

How about a new troop who acts like the king/queen? Meaning one that can defend and attack-- The Troll. I was thinking something along the lines of the troll in "Snow white and the Huntsman".One that blends in to the surrounding area then defends when troops approach. The more you upgrade, obviously the more damage it does, but also the more it "blends" in.
On offense, when the troop is placed, when maxed, all you would see is a faint outline and possibly a blur when dropped. When it's time to attcack it shows its ugly head.

thoughts?