Goliath Daydreamer is a rare Creature — Giant Wizard card from Lorwyn Eclipsed Promos (PECL), collector number 143p. Current market price: $0.61 (foil $3.69), TCGplayer market prices via Scryfall.
Whenever you cast an instant or sorcery spell from your hand, exile that card with a dream counter on it instead of putting it into your graveyard as it resolves. Whenever this creature attacks, you may cast a spell from among cards you own in exile with dream counters on them without paying its mana cost.