Basilica Screecher

Flying
Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Accursed Spirit

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)

Daggerdrome Imp

Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Contaminated Ground

Enchant land
Enchanted land is a Swamp.
Whenever enchanted land becomes tapped, its controller loses 2 life.

Corpse Blockade

Defender
Sacrifice another creature: Corpse Blockade gains deathtouch until end of turn.

Sinister Possession

Enchant creature
Whenever enchanted creature attacks or blocks, its controller loses 2 life.

Child of Night

Sign in Blood

Target player draws two cards and loses 2 life.

Bloodhunter Bat

Flying
When Bloodhunter Bat enters, target player loses 2 life and you gain 2 life.

Cremate

Exile target card from a graveyard.
Draw a card.

Ashnod's Intervention

Until end of turn, target creature gets +2/+0 and gains "When this creature dies or is put into exile from the battlefield, return it to its owner's hand."

Rotfeaster Maggot

When Rotfeaster Maggot enters, exile target creature card from a graveyard. You gain life equal to that card's toughness.

Deviant Glee

Enchant creature
Enchanted creature gets +2/+1 and has "{R}: This creature gains trample until end of turn."

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.)