Avacyn, Guardian Angel is a rare Legendary Creature — Angel card from Magic 2015 (M15), collector number 3. Current market price: $1.65 (foil $5.70), TCGplayer market prices via Scryfall.
Flying, vigilance {1}{W}: Prevent all damage that would be dealt to another target creature this turn by sources of the color of your choice. {5}{W}{W}: Prevent all damage that would be dealt to target player or planeswalker this turn by sources of the color of your choice.