Swamp

Exquisite Blood

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

Sol Ring

Diabolic Tutor

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

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Arcane Signet

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

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.

Sanguine Bond

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

Command Tower

Pristine Talisman

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.

Green Mana Battery

{2}, {T}: Put a charge counter on Green Mana Battery.
{T}, Remove any number of charge counters from Green Mana Battery: Add {G}, then add an additional {G} for each charge counter removed this way.