Last Gasp

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

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.

Poisonbelly Ogre

Whenever another creature enters, its controller loses 1 life.

Festering Wound

Enchant creature
At the beginning of your upkeep, you may put an infection counter on Festering Wound.
At the beginning of the upkeep of enchanted creature's controller, Festering Wound deals X damage to that player, where X is the number of infection counters on Festering Wound.

Blood Seeker

Whenever a creature an opponent controls enters, you may have that player lose 1 life.

Swamp

Rend Flesh

Everglades

Everglades enters tapped.
When Everglades enters, sacrifice it unless you return an untapped Swamp you control to its owner's hand.
{T}: Add {C}{B}.

Thrashing Wumpus

{B}: Thrashing Wumpus deals 1 damage to each creature and each player.

Douse in Gloom

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

Curse of Wizardry

As Curse of Wizardry enters, choose a color.
Whenever a player casts a spell of the chosen color, that player loses 1 life.