Aetherstorm Roc is a rare Creature — Bird card from Modern Horizons 3 Commander (M3C), collector number 164. Current market price: $0.27, TCGplayer market prices via Scryfall.
Flying Whenever this creature or another creature you control enters, you get {E} (an energy counter). Whenever this creature 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.