Professor Onyx — Duskmourn: House of Horror Commander #153

Magecraft — Whenever you cast or copy an instant or sorcery spell, each opponent loses 2 life and you gain 2 life.

+1: You lose 1 life. Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

−3: Each opponent sacrifices a creature with the greatest power among creatures that player controls.

−8: Each opponent may discard a card. If they don't, they lose 3 life. Repeat this process six more times.