Grenzo, Havoc Raiser is a rare Legendary Creature — Goblin Rogue card from Conspiracy: Take the Crown (CN2), collector number 54. Current market price: $0.51 (foil $4.27), TCGplayer market prices via Scryfall.
Whenever a creature you control deals combat damage to a player, choose one — • Goad target creature that player controls. • Exile the top card of that player's library. Until end of turn, you may cast that card and you may spend mana as though it were mana of any color to cast that spell.