Nightcreep

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

Plagued Rusalka

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

Keening Banshee

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

Mausoleum Turnkey

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

Bond of Agony

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

Cryptwailing

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

Smogsteed Rider

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

Caustic Rain

Undercity Shade

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

Carrion Howler

Pay 1 life: This creature gets +2/-1 until end of turn.

Vindictive Mob

When this creature enters, sacrifice a creature.
This creature can't be blocked by Saprolings.

Drekavac

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

Daggerclaw Imp

Hissing Miasma

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

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.