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.

Vraan, Executioner Thane

Whenever one or more other creatures you control die, each opponent loses 2 life and you gain 2 life. This ability triggers only once each turn.

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

Target player draws two cards and loses 2 life.

Tendrils of Corruption deals X damage to target creature and you gain X life, where X is the number of Swamps you control.

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

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

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

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

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

Flying
Whenever a creature an opponent controls dies, you may gain 3 life.
Whenever an opponent discards a card, you may gain 3 life.

Whenever you gain life, each opponent loses 1 life.

Each opponent loses 3 life. You gain life equal to the life lost this way.

Search your library for a card, then shuffle and put that card on top. You lose 2 life.