Sanguine Bond

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

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Mountain

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Sol Ring

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Edgar Markov

Eminence — Whenever you cast another Vampire spell, if Edgar Markov is in the command zone or on the battlefield, create a 1/1 black Vampire creature token.
First strike, haste
Whenever Edgar Markov attacks, put a +1/+1 counter on each Vampire you control.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.