Command Tower

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

Essence Warden

Whenever another creature enters, you gain 1 life.

Sanguine Bond

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

Arcane Signet

Golgari Signet

Vito, Thorn of the Dusk Rose

Whenever you gain life, target opponent loses that much life.
{3}{B}{B}: Creatures you control gain lifelink until end of turn.

Dina, Soul Steeper

Whenever you gain life, each opponent loses 1 life.
{1}, Sacrifice another creature: Dina, Soul Steeper gets +X/+0 until end of turn, where X is the sacrificed creature's power.

Exquisite Blood

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

Jungle Hollow

Jungle Hollow enters tapped.
When Jungle Hollow enters, you gain 1 life.
{T}: Add {B} or {G}.

Zulaport Cutthroat

Whenever Zulaport Cutthroat or another creature you control dies, each opponent loses 1 life and you gain 1 life.