Bottomless Pit

At the beginning of each player's upkeep, that player discards a card at random.

Yawgmoth's Will

Until end of turn, you may play lands and cast spells from your graveyard.
If a card would be put into your graveyard from anywhere this turn, exile that card instead.

Tainted Aether

Whenever a creature enters, its controller sacrifices a creature or land of their choice.

Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Erebos, God of the Dead

Indestructible
As long as your devotion to black is less than five, Erebos isn't a creature. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)
Your opponents can't gain life.
{1}{B}, Pay 2 life: Draw a card.

Ophiomancer

At the beginning of each upkeep, if you control no Snakes, create a 1/1 black Snake creature token with deathtouch.

Glacial Chasm

Cumulative upkeep—Pay 2 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Glacial Chasm enters, sacrifice a land.
Creatures you control can't attack.
Prevent all damage that would be dealt to you.

Polluted Bonds

Whenever a land an opponent controls enters, that player loses 2 life and you gain 2 life.

No Mercy

Whenever a creature deals damage to you, destroy it.

Gibbering Descent

At the beginning of each player's upkeep, that player loses 1 life and discards a card.
Hellbent — Skip your upkeep step if you have no cards in hand.
Madness {2}{B}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Vampire Nighthawk

Flying
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Mindslicer

When Mindslicer dies, each player discards their hand.

Oppression

Whenever a player casts a spell, that player discards a card.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Cunning Lethemancer

At the beginning of your upkeep, each player discards a card.

Ward of Bones

Each opponent who controls more creatures than you can't cast creature spells. The same is true for artifacts and enchantments.
Each opponent who controls more lands than you can't play lands.

Words of Waste

{1}: The next time you would draw a card this turn, each opponent discards a card instead.

Exsanguinate

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

Waste Not

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

Myojin of Night's Reach

Myojin of Night's Reach enters with a divinity counter on it if you cast it from your hand.
Myojin of Night's Reach has indestructible as long as it has a divinity counter on it.
Remove a divinity counter from Myojin of Night's Reach: Each opponent discards their hand.

Lethal Vapors

Whenever a creature enters, destroy it.
{0}: Destroy Lethal Vapors. You skip your next turn. Any player may activate this ability.