Goblin Kaboomist is a rare Creature — Goblin Warrior card from Magic 2015 (M15), collector number 144. Current market price: $0.51 (foil $1.21), TCGplayer market prices via Scryfall.
At the beginning of your upkeep, create a colorless artifact token named Land Mine with "{R}, Sacrifice this token: This token deals 2 damage to target attacking creature without flying." Then flip a coin. If you lose the flip, this creature deals 2 damage to itself.