Yahenni, Undying Partisan

Haste
Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni, Undying Partisan.
Sacrifice another creature: Yahenni gains indestructible until end of turn.

Charismatic Conqueror

Vigilance
Whenever an artifact or creature an opponent controls enters untapped, they may tap that permanent. If they don't, you create a 1/1 white Vampire creature token with lifelink.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Welcoming Vampire

Flying
Whenever one or more other creatures you control with power 2 or less enter, draw a card. This ability triggers only once each turn.

Bloodghast

Bloodghast can't block.
Bloodghast has haste as long as an opponent has 10 or less life.
Landfall — Whenever a land you control enters, you may return Bloodghast from your graveyard to the battlefield.

Cordial Vampire

Whenever Cordial Vampire or another creature dies, put a +1/+1 counter on each Vampire you control.

Bartolomé del Presidio

Sacrifice another creature or artifact: Put a +1/+1 counter on Bartolomé del Presidio.

Carmen, Cruel Skymarcher

Flying
Whenever a player sacrifices a permanent, put a +1/+1 counter on Carmen, Cruel Skymarcher and you gain 1 life.
Whenever Carmen attacks, return up to one target permanent card with mana value less than or equal to Carmen's power from your graveyard to the battlefield.