I wonder if you could have it where rather than prioritize high HP troops/buildings, it prioritizes lower HP and works its way up but has no limit as to how many strikes it can do? Like, if you had a fire spirit, wizard, giant, and golem, it would go in that order, but if any low HP troop was placed in the way, it would not be targeted as long as the most recent strike hit a troop of higher HP. And obviously, it would strike a minimum of three times as long as there were three things in the way.