Teval, Arbiter of Virtue is a mythic Legendary Creature — Spirit Dragon card from Tarkir: Dragonstorm Promos (PTDM), collector number 230p. Current market price: $0.72 (foil $1.28), TCGplayer market prices via Scryfall.
Flying, lifelink Spells you cast have delve. (Each card you exile from your graveyard while casting those spells pays for {1}.) Whenever you cast a spell, you lose life equal to its mana value.