Spiteful Returned

Bestow {3}{B} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Whenever this creature or enchanted creature attacks, defending player loses 2 life.
Enchanted creature gets +1/+1.

Midnight Scavengers

When this creature enters, you may return target creature card with mana value 3 or less from your graveyard to your hand.
(Melds with Graf Rats.)

Despoiler of Souls

This creature can't block.
{B}{B}, Exile two other creature cards from your graveyard: Return this card from your graveyard to the battlefield.

Paragon of Open Graves

Other black creatures you control get +1/+1.
{2}{B}, {T}: Another target black creature you control gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Swamp

Murderous Compulsion

Destroy target tapped creature.
Madness {1}{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.)

Death Wind

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

Graf Rats

At the beginning of combat on your turn, if you both own and control this creature and a creature named Midnight Scavengers, exile them, then meld them into Chittering Host.

Silumgar Assassin

Creatures with power greater than this creature's power can't block it.
Megamorph {2}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)
When this creature is turned face up, destroy target creature with power 3 or less an opponent controls.

Tormented Hero

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

Nameless Inversion

Changeling (This card is every creature type.)
Target creature gets +3/-3 and loses all creature types until end of turn.

Herald of Torment

Bestow {3}{B}{B} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Flying
At the beginning of your upkeep, you lose 1 life.
Enchanted creature gets +3/+3 and has flying.