Light of the Legion is a rare Creature — Angel card from Guilds of Ravnica (GRN), collector number 19. Current market price: $0.26 (foil $0.49), TCGplayer market prices via Scryfall.
Flying Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.) When this creature dies, put a +1/+1 counter on each white creature you control.