Turret Spell

The idea is a spell that targets defenses (primarily defenses that are actively firing at something). The spell will spawn a large balloon to hover over the target area. The balloon will have an xbow turret mounted on it that would fire at nearby defenses. It would identify primary threats and shoot first at defenses that are firing at offensive troops/heroes. If/when the turret destroys a defensive structure, it will turn and attack the next primary target.

The turret balloon would either need to act like a troop (meaning it would need to be destroyed by defenses to stop it), or be timed (and would disappear after a number of seconds). Power and attack speed (perhaps even firing radius) numbers would be dependent on the spell level.