Vito, Thorn of the Dusk Rose

Whenever you gain life, target opponent loses that much life.
{3}{B}{B}: Creatures you control gain lifelink until end of turn.

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

Whenever an opponent loses life, you gain that much life.

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: Aetherflux Reservoir deals 50 damage to any target.

Whenever you gain life, target opponent loses that much life.

Flying
If an opponent would lose life during your turn, they lose twice that much life instead. (Damage causes loss of life.)

Whenever you cast a spell, untap all nonland permanents you control.

Destroy target nonblack creature.
At the beginning of your next upkeep, pay {2}{B}. If you don't, you lose the game.