Aetherstorm Roc [Kaladesh Prerelease Promos]

Set: Kaladesh Prerelease Promos Type: Creature — Bird Rarity: Rare Cost: {2}{W}{W} FlyingWhenever Aetherstorm Roc or another creature enters the battlefield under your control, you get {E} (an energy counter).Whenever Aetherstorm Roc attacks, you may pay {E}{E}. If you do, put a +1/+1 counter on it and tap up to one target creature defending player controls.