Ruinous Waterbending (TLA)

Sorcery — Lesson

As an additional cost to cast this spell, you may waterbend {4}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.) All creatures get -2/-2 until end of turn. If this spell's additional cost was paid, whenever a creature dies this turn, you gain 1 life.

Niche board wipe for black control and sacrifice strategies, but the waterbend mechanic adds inconsistent cost and the -2/-2 effect is easily outclassed by unconditional removal like Liliana of the Veil or Damnation in most formats. The life gain rider only triggers if you pay the optional cost, making it a win-more effect in matchups where you're already ahead.

Avatar: The Last Airbender — Uncommon