The Book of Exalted Deeds is a mythic Legendary Artifact — Book card from Adventures in the Forgotten Realms (AFR), collector number 4. Current market price: $8.75 (foil $10.15), TCGplayer market prices via Scryfall.
At the beginning of your end step, if you gained 3 or more life this turn, create a 3/3 white Angel creature token with flying. {W}{W}{W}, {T}, Exile The Book of Exalted Deeds: Put an enlightened counter on target Angel. It gains "You can't lose the game and your opponents can't win the game." Activate only as a sorcery.