Have

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Staff of the Death Magus

Whenever you cast a black spell or a Swamp you control enters, you gain 1 life.

Bloodhunter Bat

Flying
When this creature enters, target player loses 2 life and you gain 2 life.

Vengeful Bloodwitch

Whenever this creature or another creature you control dies, target opponent loses 1 life and you gain 1 life.

In Garruk's Wake

Destroy all creatures you don't control and all planeswalkers you don't control.

Vampire Nighthawk

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Sanguine Bond

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

Sign in Blood

Target player draws two cards and loses 2 life.

Exquisite Blood

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

Swamp

Typhoid Rats

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

High Market

{T}: Add {C}.
{T}, Sacrifice a creature: You gain 1 life.

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Sanguine Syphoner

Whenever this creature attacks, each opponent loses 1 life and you gain 1 life.

Terramorphic Expanse

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Evolving Wilds

Night's Whisper

Reliquary Tower

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

Eternal Thirst

Enchant creature
Enchanted creature has lifelink and "Whenever a creature an opponent controls dies, put a +1/+1 counter on this creature." (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)