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.

Moriok Scavenger

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

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.

Grinding Station

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

Nested Ghoul

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

Moriok Rigger

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

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.

Vermiculos

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

Underworld Dreams

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

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.)

Nim Shambler

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

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.)

Megrim

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

Disciple of the Vault

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

Painful Quandary

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

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.

Painsmith

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

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.

Swamp

Necrogen Spellbomb

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

Nim Replica

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