Haldan, Avid Arcanist is a mythic Legendary Creature — Human Wizard card from Commander 2020 (C20), collector number 2. Current market price: $0.68 (foil $0.53), TCGplayer market prices via Scryfall.
Partner with Pako, Arcane Retriever (When this creature enters, target player may put Pako into their hand from their library, then shuffle.) You may play lands and cast noncreature spells from among cards you exiled that have fetch counters on them, and you may spend mana as though it were mana of any color to cast those spells.