Mizzix of the Izmagnus is a rare Legendary Creature — Goblin Wizard card from Commander Masters (CMM), collector number 348. Current market price: $1.04 (foil $1.69), TCGplayer market prices via Scryfall.
Whenever you cast an instant or sorcery spell with mana value greater than the number of experience counters you have, you get an experience counter. Instant and sorcery spells you cast cost {1} less to cast for each experience counter you have.