Olivia's Wrath

Each non-Vampire creature gets -X/-X until end of turn, where X is the number of Vampires you control.

Olivia's Attendants

Menace
Whenever Olivia's Attendants deals damage, create that many Blood tokens. (They're artifacts with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
{2}{R}: Olivia's Attendants deals 1 damage to any target.

Markov Enforcer

Whenever Markov Enforcer or another Vampire you control enters, Markov Enforcer fights up to one target creature an opponent controls.
Whenever a creature dealt damage by Markov Enforcer this turn dies, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Scion of Opulence

Whenever Scion of Opulence or another nontoken Vampire you control dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
{R}, Sacrifice two artifacts: Exile the top card of your library. You may play that card this turn.

Bloodbat Summoner

Flying
At the beginning of combat on your turn, up to one target Blood token you control becomes a 2/2 black Bat creature with flying and haste in addition to its other types.

Voldaren Bloodcaster

Flying
Whenever Voldaren Bloodcaster or another nontoken creature you control dies, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
Whenever you create a Blood token, if you control five or more Blood tokens, transform Voldaren Bloodcaster.

Voldaren Bloodcaster // Bloodbat Summoner

Crossway Troublemakers

Attacking Vampires you control have deathtouch and lifelink. (Any amount of damage they deal to a creature is enough to destroy it. Damage dealt by those creatures also causes their controller to gain that much life.)
Whenever a Vampire you control dies, you may pay 2 life. If you do, draw a card.

Olivia, Crimson Bride

Flying, haste
Whenever Olivia, Crimson Bride attacks, return target creature card from your graveyard to the battlefield tapped and attacking. It gains "When you don't control a legendary Vampire, exile this creature."

Strefan, Maurer Progenitor

Flying
At the beginning of your end step, create a Blood token for each player who lost life this turn.
Whenever Strefan attacks, you may sacrifice two Blood tokens. If you do, you may put a Vampire card from your hand onto the battlefield tapped and attacking. It gains indestructible until end of turn.

Bloodvial Purveyor

Flying, trample
Whenever an opponent casts a spell, that player creates a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
Whenever Bloodvial Purveyor attacks, it gets +1/+0 until end of turn for each Blood token defending player controls.

Anje, Maid of Dishonor

Whenever Anje, Maid of Dishonor and/or one or more other Vampires you control enter, create a Blood token. This ability triggers only once each turn. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")
{2}, Sacrifice another creature or a Blood token: Each opponent loses 2 life and you gain 2 life.