You should implement a Flame Thrower. It would take a large chunk of energy, like maybe 100 energy, but you use it in an area with a lot of trees and it catches a bunch of trees on fire, knocking off a few levels from each tree at the same time until the fire goes out. Say you have 5 fully grown trees, use the flame thrower on them, and it takes a couple levels off each one for 100 or so energy until the flames extinguish themselves. Adding cool new features like this would make the darn so much more fun.