Hammer Jammer is a uncommon Creature — Goblin Warrior card from Unstable (UST), collector number 86. Current market price: $0.13 (foil $2.50), TCGplayer market prices via Scryfall.
As this creature enters, roll a six-sided die. This creature enters with a number of +1/+1 counters on it equal to the result. Whenever you roll a die, remove all +1/+1 counters from this creature, then put a number of +1/+1 counters on it equal to the result.