Angelic Intervention is a common Instant card from March of the Machine (MOM), collector number 5. Current market price: $0.24 (foil $0.28), TCGplayer market prices via Scryfall.
Target creature or planeswalker you control gains protection from colorless or from the color of your choice until end of turn. If it's a creature, put a +1/+1 counter on it. (It can't be blocked, targeted, dealt damage, enchanted, or equipped by anything with that quality.)