Prime Speaker Vannifar
Ravnica Allegiance — mythic
Legendary Creature — Elf Ooze Wizard
Prime Speaker Vannifar rulings:
2019-01-25: If a creature or a creature card in your library has in its mana cost, X is considered to be 0.
2019-01-25: Tokens that aren’t a copy of something else don’t have a mana cost. Anything without a mana cost normally has a converted mana cost of 0.