The Scarlet Witch is a rare Legendary Creature — Mutant Warlock Hero card from Marvel Super Heroes (MSH), collector number 368. Current market price: $2.15 (foil $3.89), TCGplayer market prices via Scryfall.
Instant and sorcery spells you cast with mana value 4 or greater cost {X} less to cast, where X is The Scarlet Witch's power.