Contagious Nim

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Megrim

Whenever an opponent discards a card, Megrim deals 2 damage to that player.

Salvaging Station

{T}: Return target noncreature artifact card with mana value 1 or less from your graveyard to the battlefield.
Whenever a creature dies, you may untap Salvaging Station.

Phyrexian Juggernaut

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Phyrexian Juggernaut attacks each combat if able.

Nim Shambler

Nim Shambler gets +1/+0 for each artifact you control.
Sacrifice a creature: Regenerate Nim Shambler.

Ob Nixilis of the Black Oath

+2: Each opponent loses 1 life. You gain life equal to the life lost this way.
−2: Create a 5/5 black Demon creature token with flying. You lose 2 life.
−8: You get an emblem with "{1}{B}, Sacrifice a creature: You gain X life and draw X cards, where X is the sacrificed creature's power."
Ob Nixilis of the Black Oath can be your commander.

Painful Quandary

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

Nim Replica

{2}{B}, Sacrifice Nim Replica: Target creature gets -1/-1 until end of turn.

Contamination

At the beginning of your upkeep, sacrifice Contamination unless you sacrifice a creature.
If a land is tapped for mana, it produces {B} instead of any other type and amount.

Disciple of the Vault

Whenever an artifact is put into a graveyard from the battlefield, you may have target opponent lose 1 life.

Moriok Rigger

Whenever an artifact is put into a graveyard from the battlefield, you may put a +1/+1 counter on Moriok Rigger.

Toxic Nim

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{B}: Regenerate Toxic Nim.

Necrogen Spellbomb

{B}, Sacrifice Necrogen Spellbomb: Target player discards a card.
{1}, Sacrifice Necrogen Spellbomb: Draw a card.

Order of Yawgmoth

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever Order of Yawgmoth deals damage to a player, that player discards a card.

Reaper of Sheoldred

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever a source deals damage to Reaper of Sheoldred, that source's controller gets a poison counter.

Painsmith

Whenever you cast an artifact spell, you may have target creature get +2/+0 and gain deathtouch until end of turn.

Swamp

Underworld Dreams

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.

Vermiculos

Whenever an artifact enters, Vermiculos gets +4/+4 until end of turn.

Contaminated Bond

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Whenever enchanted creature attacks or blocks, its controller loses 3 life.

Moriok Scavenger

When Moriok Scavenger enters, you may return target artifact creature card from your graveyard to your hand.

Nested Ghoul

Whenever a source deals damage to Nested Ghoul, create a 2/2 black Phyrexian Zombie creature token.

Grinding Station

{T}, Sacrifice an artifact: Target player mills three cards.
Whenever an artifact enters, you may untap Grinding Station.

Wire Surgeons

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Each artifact creature card in your graveyard has encore. Its encore cost is equal to its mana cost. (Exile it and pay its mana cost: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)