Otaria is a common Plane — Dominaria card from Planechase Anthology Planes (OPCA), collector number 61. Current market price: $4.34, TCGplayer market prices via Scryfall.
Instant and sorcery cards in graveyards have flashback. The flashback cost is equal to the card's mana cost. (Its owner may cast the card from their graveyard for its mana cost. Then they exile it.) Whenever chaos ensues, take an extra turn after this one.