Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight - Legendary

Flying, lifelink Creature spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting a creature spell pays for {1} or one mana of that creature's color.) At the beginning of your first main phase, you may pay {B}. If you do, transform Eirdu.