Screaming Swarm is a uncommon Creature — Bird Horror card from Innistrad: Double Feature (DBL), collector number 342. Current market price: $0.28 (foil $0.72), TCGplayer market prices via Scryfall.
Flying Whenever you attack with one or more creatures, target player mills that many cards. (To mill a card, a player puts the top card of their library into their graveyard.) {2}{U}: Put this card from your graveyard into your library second from the top.