Prismari Pianist

• WWizards of the Coast2026-03-20
  Official Ruling
  For spells on the stack with in their mana costs, use the value chosen for X to determine the spell's mana value.
• WWizards of the Coast2026-03-20
  Official Ruling
  A spell's mana value is determined only by its mana cost. Ignore any alternative costs, additional costs, cost increases, or cost reductions.
• WWizards of the Coast2026-03-20
  Official Ruling
  Prismari Pianist's ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered or otherwise leaves the stack without resolving.

Rulings via Scryfall