Uvilda, Dean of Perfection

Nassari’s last ability triggers when you cast any spell from exile, not just the cards that were exiled with its first ability.

Any cards exiled with Nassari’s ability that you don’t cast will remain exiled. You won’t be able to cast those cards on future turns, although Nassari’s ability will give you another group of cards to choose from each time it resolves.

To determine the total cost of a spell, start with the mana cost or alternative cost you’re paying, add any cost increases, then apply any cost reductions (such as that of Uvilda, Dean of Perfection). The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.