Marcille, Top of Her Class

Magecraft — When you cast an instant or sorcery spell, create a 0/1 blue Spirit token with defender, flying, and "Sacrifice this creature: Add one mana of any color."

Marcille's power is equal to the number of Spirit tokens
you control.

{x}: Return target creature from your graveyard to the battlefield, where X is that creature's mana value. Spend only black mana this way.

"I specialize in the study of ancient magic that's forbidden now."