Stormtide Leviathan is a rare Creature — Leviathan card from Magic 2011 (M11), collector number 74. Current market price: $0.66 (foil $3.98), TCGplayer market prices via Scryfall.
Islandwalk (This creature can't be blocked as long as defending player controls an Island.) All lands are Islands in addition to their other types. Creatures without flying or islandwalk can't attack.