Realmwalker is a rare Creature — Shapeshifter card from The Lost Caverns of Ixalan Commander (LCC), collector number 250. Current market price: $2.42, TCGplayer market prices via Scryfall.
Changeling (This card is every creature type.) As this creature enters, choose a creature type. You may look at the top card of your library any time. You may cast creature spells of the chosen type from the top of your library.