Haldan, Avid Arcanist [Commander 2020]

Partner with Pako, Arcane Retriever (When this creature enters the battlefield, target player may put Pako into their hand from their library, then shuffle.)
You may play noncreature cards from exile with fetch counters on them if you exiled them, and you may spend mana as though it were mana of any color to cast those spells.