Discontinuity is a mythic Instant card from Core Set 2021 (M21), collector number 349. Current market price: $2.22 (foil $2.70), TCGplayer market prices via Scryfall.
During your turn, this spell costs {2}{U}{U} less to cast. End the turn. (Exile all spells and abilities from the stack, including this card. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)