Errant Ephemeron is a common Creature — Illusion card from Modern Masters (MMA), collector number 41. Current market price: $0.21 (foil $0.32), TCGplayer market prices via Scryfall.
Flying Suspend 4—{1}{U} (Rather than cast this card from your hand, you may pay {1}{U} and exile it with four time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)