Spellbound Dragon is a rare Creature — Dragon card from Alara Reborn (ARB), collector number 90. Current market price: $0.38 (foil $2.58), TCGplayer market prices via Scryfall.
Flying Whenever this creature attacks, draw a card, then discard a card. This creature gets +X/+0 until end of turn, where X is the discarded card's mana value.