Blood Seeker

Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Tithe Drinker

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Arrogant Outlaw

When this creature enters, if an opponent lost life this turn, each opponent loses 2 life and you gain 2 life.

Sanguine Syphoner

Whenever this creature attacks, each opponent loses 1 life and you gain 1 life.

Vampire Neonate

{2}, {T}: Each opponent loses 1 life and you gain 1 life.

Vampire Spawn

When this creature enters, each opponent loses 2 life and you gain 2 life.

Serrated Scorpion

When this creature dies, it deals 2 damage to each opponent and you gain 2 life.

Basilica Screecher

Flying
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Wispdrinker Vampire

Flying
Whenever another creature you control with power 2 or less enters, each opponent loses 1 life and you gain 1 life.
{5}{W}{B}: Creatures you control with power 2 or less gain deathtouch and lifelink until end of turn.

Sanguine Savior

Flying, lifelink
Disguise {W/B}{W/B} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)
When this creature is turned face up, another target creature you control gains lifelink until end of turn.

Vampire Envoy

Flying
Whenever this creature becomes tapped, you gain 1 life.

Pulse Tracker

Whenever this creature attacks, each opponent loses 1 life.

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.