Death Pulse

Target creature gets -4/-4 until end of turn.
Cycling {1}{B}{B} ({1}{B}{B}, Discard this card: Draw a card.)
When you cycle Death Pulse, you may have target creature get -1/-1 until end of turn.

Shambling Swarm

When Shambling Swarm dies, distribute three -1/-1 counters among one, two, or three target creatures. For each -1/-1 counter you put on a creature this way, remove a -1/-1 counter from that creature at the beginning of the next end step.

Dirge of Dread

All creatures gain fear until end of turn. (They can't be blocked except by artifact creatures and/or black creatures.)
Cycling {1}{B} ({1}{B}, Discard this card: Draw a card.)
When you cycle Dirge of Dread, you may have target creature gain fear until end of turn.

Lose Hope

Target creature gets -1/-1 until end of turn. Scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Profane Command

Choose two —
• Target player loses X life.
• Return target creature card with mana value X or less from your graveyard to the battlefield.
• Target creature gets -X/-X until end of turn.
• Up to X target creatures gain fear until end of turn. (They can't be blocked except by artifact creatures and/or black creatures.)

Gravebind

Target creature can't be regenerated this turn.
Draw a card at the beginning of the next turn's upkeep.

Festering Mummy

When Festering Mummy dies, you may put a -1/-1 counter on target creature.

Nighthaze

Target creature gains swampwalk until end of turn. (It can't be blocked as long as defending player controls a Swamp.)
Draw a card.

Dauthi Trapper

{T}: Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)

Word of Binding

Tragic Slip

Target creature gets -1/-1 until end of turn.
Morbid — That creature gets -13/-13 until end of turn instead if a creature died this turn.

Scuttlemutt

{T}: Add one mana of any color.
{T}: Target creature becomes the color or colors of your choice until end of turn.

Festering Goblin

When Festering Goblin dies, target creature gets -1/-1 until end of turn.

Rouse

If you control a Swamp, you may pay 2 life rather than pay this spell's mana cost.
Target creature gets +2/+0 until end of turn.

Tetzimoc, Primal Death

Deathtouch
{B}, Reveal Tetzimoc, Primal Death from your hand: Put a prey counter on target creature. Activate only during your turn.
When Tetzimoc enters, destroy each creature your opponents control with a prey counter on it.

Afflict

Target creature gets -1/-1 until end of turn.
Draw a card.

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.