Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Timothar, Baron of Bats

Ward—Discard a card.
Whenever another nontoken Vampire you control dies, you may pay {1} and exile it. If you do, create a 1/1 black Bat creature token with flying. It gains "When this creature deals combat damage to a player, sacrifice it and return the exiled card to the battlefield tapped."

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.

Creeping Bloodsucker

At the beginning of your upkeep, Creeping Bloodsucker deals 1 damage to each opponent. You gain life equal to the damage dealt this way.

Exquisite Blood

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

Sanguine Bond

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