Overclocked Electromancer [M3C-110]

At the beginning of combat on your turn, you may pay {E}{E}{E}. If you do, put a +1/+1 counter on Overclocked Electromancer. Whenever Overclocked Electromancer attacks, double its power until end of turn. Whenever Overclocked Electromancer deals combat damage to a creature, if that creature was dealt excess damage this turn, you get X {E}, where X is that excess damage.