Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.

Darksteel Citadel

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Wasteland

{T}: Add {C}.
{T}, Sacrifice Wasteland: Destroy target nonbasic land.

Vault Skirge

({B/P} can be paid with either {B} or 2 life.)
Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Scrapyard Recombiner

Modular 2 (This creature enters the battlefield with two +1/+1 counters on it. When it dies, you may put its +1/+1 counters on target artifact creature.)
{T}, Sacrifice an artifact: Search your library for a Construct card, reveal it, put it into your hand, then shuffle.

Walking Ballista

Walking Ballista enters the battlefield with X +1/+1 counters on it.
{4}: Put a +1/+1 counter on Walking Ballista.
Remove a +1/+1 counter from Walking Ballista: It deals 1 damage to any target.

Karakas

{T}: Add {W}.
{T}: Return target legendary creature to its owner's hand.

Steel Overseer

{T}: Put a +1/+1 counter on each artifact creature you control.

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Arcbound Ravager

Sacrifice an artifact: Put a +1/+1 counter on Arcbound Ravager.
Modular 1 (This creature enters the battlefield with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Mishra's Factory

{T}: Add {C}.
{1}: Mishra's Factory becomes a 2/2 Assembly-Worker artifact creature until end of turn. It's still a land.
{T}: Target Assembly-Worker creature gets +1/+1 until end of turn.

Karn, the Great Creator

Activated abilities of artifacts your opponents control can't be activated.
+1: Until your next turn, up to one target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value.
−2: You may reveal an artifact card you own from outside the game or choose a face-up artifact card you own in exile. Put that card into your hand.

Thorn of Amethyst

Noncreature spells cost {1} more to cast.

Stonecoil Serpent

Reach, trample, protection from multicolored
Stonecoil Serpent enters the battlefield with X +1/+1 counters on it.

City of Traitors

When you play another land, sacrifice City of Traitors.
{T}: Add {C}{C}.

Seat of the Synod

Chalice of the Void

Chalice of the Void enters the battlefield with X charge counters on it.
Whenever a player casts a spell with mana value equal to the number of charge counters on Chalice of the Void, counter that spell.

Mycosynth Lattice

All permanents are artifacts in addition to their other types.
All cards that aren't on the battlefield, spells, and permanents are colorless.
Players may spend mana as though it were mana of any color.

Phyrexian Revoker

As Phyrexian Revoker enters the battlefield, choose a nonland card name.
Activated abilities of sources with the chosen name can't be activated.