Evelyn, the Covetous

Flash
Whenever Evelyn, the Covetous or another Vampire you control enters, exile the top card of each player's library with a collection counter on it.
Once each turn, you may play a card from exile with a collection counter on it if it was exiled by an ability you controlled, and you may spend mana as though it were mana of any color to cast it.

Obosh, the Preypiercer

Companion — Your starting deck contains only cards with odd mana values and land cards. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
If a source you control with an odd mana value would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Arrogant Outlaw

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

Belligerent Guest

Trample
Whenever Belligerent Guest deals combat damage to a player, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Bishop of the Bloodstained

When Bishop of the Bloodstained enters, target opponent loses 1 life for each Vampire you control.

Blood Glutton

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

Blood Hypnotist

Blood Hypnotist can't block.
Whenever you sacrifice one or more Blood tokens, target creature can't block this turn. This ability triggers only once each turn.

Bloodthirsty Aerialist

Flying
Whenever you gain life, put a +1/+1 counter on Bloodthirsty Aerialist.

Defiant Bloodlord

Flying
Whenever you gain life, target opponent loses that much life.

Falkenrath Celebrants

Menace (This creature can't be blocked except by two or more creatures.)
When Falkenrath Celebrants enters, create two Blood tokens. (They're artifacts with "{1}, {T}, Discard a card, Sacrifice this artifact: Draw a card.")

Falkenrath Forebear

Flying
Falkenrath Forebear can't block.
Whenever Falkenrath Forebear deals combat damage to a player, create a Blood token.
{B}, Sacrifice two Blood tokens: Return Falkenrath Forebear from your graveyard to the battlefield.