Zombie Infestation

Discard two cards: Create a 2/2 black Zombie creature token.

Swamp

Sol Ring

Rain of Filth

Until end of turn, lands you control gain "Sacrifice this land: Add {B}."

Crystal Vein

{T}: Add {C}.
{T}, Sacrifice Crystal Vein: Add {C}{C}.

Ebon Stronghold

Ebon Stronghold enters tapped.
{T}: Add {B}.
{T}, Sacrifice Ebon Stronghold: Add {B}{B}.

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Maralen of the Mornsong

Players can't draw cards.
At the beginning of each player's draw step, that player loses 3 life, searches their library for a card, puts it into their hand, then shuffles.

Ad Nauseam

Reveal the top card of your library and put that card into your hand. You lose life equal to its mana value. You may repeat this process any number of times.

Bone Miser

Whenever you discard a creature card, create a 2/2 black Zombie creature token.
Whenever you discard a land card, add {B}{B}.
Whenever you discard a noncreature, nonland card, draw a card.