Kaza, Roil Chaser

Text:

Flying, haste
: The next instant or sorcery spell you cast this turn costs less to cast, where X is the number of Wizards you control as this ability resolves.

Rulings:

• 9/25/2020 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 Kaza’s activated ability). The converted mana cost of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.
• 9/25/2020 Kaza’s cost reduction can reduce only generic mana in a spell’s cost. It can’t reduce colored mana requirements.