Marvo, Deep Operative is a mythic Legendary Creature — Octopus Rogue card from Murders at Karlov Manor Commander (MKC), collector number 7. Current market price: — (foil $0.70), TCGplayer market prices via Scryfall.
Whenever Marvo attacks, clash with defending player. (Each clashing player reveals the top card of their library, then puts that card on their choice of the top or bottom. A player wins if their card had a greater mana value.) Whenever you win a clash, draw a card. Then you may cast a spell from your hand with mana value 8 or less without paying its mana cost.