Agonizing Remorse is a uncommon Sorcery card from Strixhaven Mystical Archive (STA), collector number 24. Current market price: $0.20 (foil $0.30), TCGplayer market prices via Scryfall.
Target opponent reveals their hand. You choose a nonland card from it or a card from their graveyard. Exile that card. You lose 1 life.