Sanguine Bond

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

Cliffhaven Vampire

Flying
Whenever you gain life, each opponent loses 1 life.

Sorin, Vengeful Bloodlord

During your turn, creatures and planeswalkers you control have lifelink.
+2: Sorin, Vengeful Bloodlord deals 1 damage to target player or planeswalker.
−X: Return target creature card with mana value X from your graveyard to the battlefield. That creature is a Vampire in addition to its other types.

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Exquisite Blood

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

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.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Ashiok, Dream Render

Spells and abilities your opponents control can't cause their controller to search their library.
−1: Target player mills four cards. Then exile each opponent's graveyard.