New Troop ideas

Sometimes you can found near the trees not only gems but special bones too. This bones are of special Troop and you can use to summon that one once. That's for introduce new Troops that rarely people can summon (they need to found that bones) and so they don't change equilibrium in the game.

Something like this would actually change the core gameplay.
If it´s a strong unit the game will all be about luck, how often people drop those bones to make strong attacks.
If it´s a weak unit without much use, it will probably be unused, so why would we need it anyway?

I think it would be hard to balance this out to get a unit that on the one hand is strong enough to really consider using it, but weak enough to not turn the battle around completley once someone is able to summon it.