Entropic Eidolon

{B}, Sacrifice Entropic Eidolon: Target player loses 1 life and you gain 1 life.
Whenever you cast a multicolored spell, you may return Entropic Eidolon from your graveyard to your hand.

Restless Bones

{3}{B}, {T}: Target creature gains swampwalk until end of turn. (It can't be blocked as long as defending player controls a Swamp.)
{1}{B}: Regenerate Restless Bones.

Disembowel

Destroy target creature with mana value X.

Macabre Waltz

Return up to two target creature cards from your graveyard to your hand, then discard a card.

Strands of Undeath

Enchant creature
When Strands of Undeath enters, target player discards two cards.
{B}: Regenerate enchanted creature.

Sewerdreg

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Sacrifice Sewerdreg: Exile target card from a graveyard.

Last Gasp

Target creature gets -3/-3 until end of turn.

Vesper Ghoul

{T}, Pay 1 life: Add one mana of any color.

Douse in Gloom

Douse in Gloom deals 2 damage to target creature and you gain 2 life.

Infectious Host

When Infectious Host dies, target player loses 2 life.

Poisonbelly Ogre

Whenever another creature enters, its controller loses 1 life.

Thoughtpicker Witch

{1}, Sacrifice a creature: Look at the top two cards of target opponent's library, then exile one of them.

Necromantic Thirst

Enchant creature
Whenever enchanted creature deals combat damage to a player, you may return target creature card from your graveyard to your hand.

Seal of Doom

Sacrifice Seal of Doom: Destroy target nonblack creature. It can't be regenerated.

Enemy of the Guildpact

Necromancer's Magemark

Enchant creature
Creatures you control that are enchanted get +1/+1.
If a creature you control that's enchanted would die, return it to its owner's hand instead.

Sadistic Augermage

When Sadistic Augermage dies, each player puts a card from their hand on top of their library.