Drekavac

When Drekavac enters, sacrifice it unless you discard a noncreature card.

Bond of Agony

As an additional cost to cast this spell, pay X life.
Each other player loses X life.

Nightcreep

Until end of turn, all creatures become black and all lands become Swamps.

Carrion Howler

Pay 1 life: Carrion Howler gets +2/-1 until end of turn.

Brain Pry

Choose a nonland card name. Target player reveals their hand. That player discards a card with that name. If they can't, you draw a card.

Daggerclaw Imp

Caustic Rain

Plagued Rusalka

{B}, Sacrifice a creature: Target creature gets -1/-1 until end of turn.

Undercity Shade

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
{B}: Undercity Shade gets +1/+1 until end of turn.

Mausoleum Turnkey

When Mausoleum Turnkey enters, return target creature card of an opponent's choice from your graveyard to your hand.

Cryptwailing

{1}, Exile two creature cards from your graveyard: Target player discards a card. Activate only as a sorcery.

Smogsteed Rider

Whenever Smogsteed Rider attacks, each other attacking creature gains fear until end of turn. (They can't be blocked except by artifact creatures and/or black creatures.)

Hissing Miasma

Whenever a creature attacks you, its controller loses 1 life.

Vindictive Mob

When Vindictive Mob enters, sacrifice a creature.
Vindictive Mob can't be blocked by Saprolings.

Keening Banshee

Flying
When Keening Banshee enters, target creature gets -2/-2 until end of turn.