Maulfist Doorbuster is a uncommon Creature — Human Warrior card from Kaladesh (KLD), collector number 123. Current market price: $0.07 (foil $0.52), TCGplayer market prices via Scryfall.
When this creature enters, you get {E}{E} (two energy counters). Whenever this creature attacks, you may pay {E}. If you do, target creature can't block this turn.