Chainer, Dementia Master

All Nightmares get +1/+1.
{B}{B}{B}, Pay 3 life: Put target creature card from a graveyard onto the battlefield under your control. That creature is black and is a Nightmare in addition to its other creature types.
When Chainer leaves the battlefield, exile all Nightmares.

Lithoform Engine

{2}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
{3}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.
{4}, {T}: Copy target permanent spell you control. (The copy becomes a token.)

Prototype Portal

Imprint — When this artifact enters, you may exile an artifact card from your hand.
{X}, {T}: Create a token that's a copy of the exiled card. X is the mana value of that card.

Mirari

Whenever you cast an instant or sorcery spell, you may pay {3}. If you do, copy that spell. You may choose new targets for the copy.

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Fateful Handoff

Draw cards equal to the mana value of target artifact or creature you control. An opponent gains control of that permanent.

Crypt Ghast

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever you tap a Swamp for mana, add an additional {B}.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Mirrorworks

Whenever another nontoken artifact you control enters, you may pay {2}. If you do, create a token that's a copy of that artifact.

Kokusho, the Evening Star

Flying
When Kokusho dies, each opponent loses 5 life. You gain life equal to the life lost this way.

Viscera Seer

Sacrifice a creature: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Swamp

Diabolic Revelation

Search your library for up to X cards, put those cards into your hand, then shuffle.

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Gray Merchant of Asphodel

When this creature 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.)

Demonic Tutor

Sculpting Steel

You may have this artifact enter as a copy of any artifact on the battlefield.

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.