Umori, the Collector (IKO-231) - Ikoria: Lair of Behemoths: (companion)

Companion — Each nonland card in your starting deck shares a card type. (If this card is your chosen companion, you may put it into your hand from outside the game for as a sorcery.)
As Umori, the Collector enters the battlefield, choose a card type.
Spells you cast of the chosen type cost less to cast.