Blood Glutton

Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Blood Seeker

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

Dusk Legion Zealot

When Dusk Legion Zealot enters, you draw a card and you lose 1 life.

Bloodcrazed Socialite

Menace
When Bloodcrazed Socialite enters, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
Whenever Bloodcrazed Socialite attacks, you may sacrifice a Blood token. If you do, it gets +2/+2 until end of turn.

Pulse Tracker

Whenever Pulse Tracker attacks, each opponent loses 1 life.

Voldaren Stinger

Voldaren Stinger has first strike as long as it's attacking.
{2}{R}: Voldaren Stinger gets +2/+0 until end of turn.

Vampire Spawn

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

Bloodmad Vampire

Whenever Bloodmad Vampire deals combat damage to a player, put a +1/+1 counter on it.
Madness {1}{R} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)