Pox Plague is a rare Sorcery card from Secrets of Strixhaven Promos (PSOS), collector number 94p. Current market price: $0.65 (foil $1.73), TCGplayer market prices via Scryfall.
Each player loses half their life, then discards half the cards in their hand, then sacrifices half the permanents they control of their choice. Round down each time.