Persistent Constrictor

At the beginning of each opponent's upkeep, they lose 1 life and you put a -1/-1 counter on up to one target creature they control.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Ascendant Evincar

Flying (This creature can't be blocked except by creatures with flying or reach.)
Other black creatures get +1/+1.
Nonblack creatures get -1/-1.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Plague Mare

Plague Mare can't be blocked by white creatures.
When Plague Mare enters, creatures your opponents control get -1/-1 until end of turn.

Plague Spitter

At the beginning of your upkeep, Plague Spitter deals 1 damage to each creature and each player.
When Plague Spitter dies, it deals 1 damage to each creature and each player.

Sol Ring

Maha, Its Feathers Night

Flying, trample
Ward—Discard a card.
Creatures your opponents control have base toughness 1.

Gruesome Realization

Choose one —
• You draw two cards and you lose 2 life.
• Creatures your opponents control get -1/-1 until end of turn.

Kaervek, the Spiteful

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

Palantír of Orthanc

At the beginning of your end step, put an influence counter on Palantír of Orthanc and scry 2. Then target opponent may have you draw a card. If that player doesn't, you mill X cards, where X is the number of influence counters on Palantír of Orthanc, and that player loses life equal to the total mana value of those cards.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Fell

Sign in Blood

Target player draws two cards and loses 2 life.

Night Clubber

When Night Clubber enters, creatures your opponents control get -1/-1 until end of turn.
Blitz {2}{B} (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)

Withering Torment

Destroy target creature or enchantment. You lose 2 life.

Swamp

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Crypt Rats

{X}: Crypt Rats deals X damage to each creature and each player. Spend only black mana on X.

Arcbound Condor

Flying
Modular 3 (This creature enters with three +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)
Whenever another artifact you control enters, target creature an opponent controls gets -1/-1 until end of turn.

Make Obsolete

Creatures your opponents control get -1/-1 until end of turn.

Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Murder

Underworld Connections

Enchant land
Enchanted land has "{T}, Pay 1 life: Draw a card."

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Jet Medallion

Black spells you cast cost {1} less to cast.

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Night of Souls' Betrayal

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Flayer Husk

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1.
Equip {2}

Contagion Engine

When Contagion Engine enters, put a -1/-1 counter on each creature target player controls.
{4}, {T}: Proliferate twice. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)

Let's Play a Game

Delirium — Choose one. If there are four or more card types among cards in your graveyard, choose one or more instead.
• Creatures your opponents control get -1/-1 until end of turn.
• Each opponent discards two cards.
• Each opponent loses 3 life and you gain 3 life.

Massacre Wurm

When Massacre Wurm enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.