Swamp

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.

Epicure of Blood

Whenever you gain life, each opponent loses 1 life.

Exquisite Blood

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

Tormented Hero

Tormented Hero enters tapped.
Heroic — Whenever you cast a spell that targets Tormented Hero, each opponent loses 1 life. You gain life equal to the life lost this way.

Arcane Signet

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

Agent of Masks

At the beginning of your upkeep, each opponent loses 1 life. You gain life equal to the life lost this way.

Suture Priest

Whenever another creature you control enters, you may gain 1 life.
Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Sol Ring

Defiant Bloodlord

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

Cliffhaven Vampire

Flying
Whenever you gain life, each opponent loses 1 life.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.