ok the idea of energy loss gave me a couple ideas :P

Spirit of Bursting Energy
15 energy, 5 sec cast, 60 second recharge.
nature ritual
expertise

create a lvl 1...8 spirit of bursting energy. whenever a creature dies in this spirits range adjacent foes take damage equal to 100%...200% of that creatures energy upon death.

kinda fun, and not too broke i think.