Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Blood Artist

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

Nirkana Assassin

Whenever you gain life, Nirkana Assassin gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Swamp

Bloodbond Vampire

Whenever you gain life, put a +1/+1 counter on Bloodbond Vampire.

Tivash, Gloom Summoner

Lifelink
At the beginning of your end step, if you gained life this turn, you may pay X life, where X is the amount of life you gained this turn. If you do, create an X/X black Demon creature token with flying.

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.

Ill-Gotten Inheritance

At the beginning of your upkeep, Ill-Gotten Inheritance deals 1 damage to each opponent and you gain 1 life.
{5}{B}, Sacrifice Ill-Gotten Inheritance: It deals 4 damage to target opponent and you gain 4 life.

Oathsworn Vampire

Oathsworn Vampire enters tapped.
You may cast Oathsworn Vampire from your graveyard if you gained life this turn.

Vampire Envoy

Flying
Whenever Vampire Envoy becomes tapped, you gain 1 life.

Ancient Craving

You draw three cards and you lose 3 life.

Thriving Moor

Thriving Moor enters tapped. As it enters, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.