Winterthorn Blessing is a uncommon Sorcery card from Innistrad: Double Feature (DBL), collector number 251. Current market price: $0.17 (foil $0.51), TCGplayer market prices via Scryfall.
Put a +1/+1 counter on up to one target creature you control. Tap up to one target creature you don't control, and that creature doesn't untap during its controller's next untap step. Flashback {1}{G}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)