Marsh Gas

All creatures get -2/-0 until end of turn.

Drudge Skeletons

{B}: Regenerate Drudge Skeletons. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Bad Moon

Spirit Shackle

Enchant creature
Whenever enchanted creature becomes tapped, put a -0/-2 counter on it.

Scathe Zombies

El-Hajjâj

Whenever El-Hajjâj deals damage, you gain that much life.

Lost Soul

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Swamp

Fear

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature has fear. (It can't be blocked except by artifact creatures and/or black creatures.)

Obsianus Golem

Unholy Strength

Enchant creature
Enchanted creature gets +2/+1.

Flying Carpet

{2}, {T}: Target creature gains flying until end of turn.

Nightmare

Whenever this creature attacks or blocks, each opponent exiles the top two cards of their library.

Howl from Beyond

Target creature gets +X/+0 until end of turn.

Black Knight

First strike (This creature deals combat damage before creatures without first strike.)
Protection from white (This creature can't be blocked, targeted, dealt damage, or enchanted by anything white.)