Flatten

Target creature gets -4/-4 until end of turn.

Devour Flesh

Target player sacrifices a creature of their choice, then gains life equal to that creature's toughness.

Grotesque Mutation

Target creature gets +3/+1 and gains lifelink until end of turn. (Damage dealt by the creature also causes its controller to gain that much life.)

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Nirkana Assassin

Whenever you gain life, Nirkana Assassin gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Tidy Conclusion

Destroy target creature. You gain 1 life for each artifact you control.

Pharika's Cure

Pharika's Cure deals 2 damage to target creature and you gain 2 life.

Essence Extraction

Essence Extraction deals 3 damage to target creature and you gain 3 life.

Stromkirk Mentor

When Stromkirk Mentor enters, put a +1/+1 counter on another target Vampire you control.

Butcher's Glee

Target creature gets +3/+0 and gains lifelink until end of turn. Regenerate it. (Damage dealt by a creature with lifelink also causes its controller to gain that much life.)

Gravepurge

Put any number of target creature cards from your graveyard on top of your library.
Draw a card.

Trespasser's Curse

Enchant player
Whenever a creature enchanted player controls enters, that player loses 1 life and you gain 1 life.

Vampire Envoy

Flying
Whenever Vampire Envoy becomes tapped, you gain 1 life.

Farbog Revenant

Skulk (This creature can't be blocked by creatures with greater power.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Foul-Tongue Shriek

Target opponent loses 1 life for each attacking creature you control. You gain that much life.

Liturgy of Blood

Alms of the Vein

Target opponent loses 3 life and you gain 3 life.
Madness {B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)