Maelstrom Wanderer is a mythic Legendary Creature — Elemental card from Magic Online Promos (PRM), collector number 86190.
Creatures you control have haste. Cascade, cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order. Then do it again.)