Overcooked Electromancer(M3C) (Modern Horizon 3)

At the beginning of combat on your turn, you may pay EEE. 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.