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.

Wasteland

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

Drownyard Temple

{T}: Add {C}.
{3}: Return this card from your graveyard to the battlefield tapped.

Mox Diamond

If this artifact would enter, you may discard a land card instead. If you do, put this artifact onto the battlefield. If you don't, put it into its owner's graveyard.
{T}: Add one mana of any color.

Smokestack

At the beginning of your upkeep, you may put a soot counter on this artifact.
At the beginning of each player's upkeep, that player sacrifices a permanent of their choice for each soot counter on this artifact.

Ensnaring Bridge

Creatures with power greater than the number of cards in your hand can't attack.

Buried Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice this land: Return target artifact card from your graveyard to your hand.

Chalice of the Void

This artifact enters with X charge counters on it.
Whenever a player casts a spell with mana value equal to the number of charge counters on this artifact, counter that spell.

Powder Keg

At the beginning of your upkeep, you may put a fuse counter on this artifact.
{T}, Sacrifice this artifact: Destroy each artifact and creature with mana value equal to the number of fuse counters on this artifact.

Crucible of Worlds

Lotus Petal

{T}, Sacrifice this artifact: Add one mana of any color.

Ancient Tomb

{T}: Add {C}{C}. This land deals 2 damage to you.

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — This Saga gains "{T}: Add {C}."
II — This Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This token gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Metalworker

{T}: Reveal any number of artifact cards in your hand. Add {C}{C} for each card revealed this way.

Tangle Wire

Fading 4 (This artifact enters with four fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
At the beginning of each player's upkeep, that player taps an untapped artifact, creature, or land they control for each fade counter on this artifact.

Myr Servitor

At the beginning of your upkeep, if this creature is on the battlefield, each player returns all cards named Myr Servitor from their graveyard to the battlefield.

City of Traitors

When you play another land, sacrifice this land.
{T}: Add {C}{C}.

Retrofitter Foundry

{3}: Untap this artifact.
{2}, {T}: Create a 1/1 colorless Servo artifact creature token.
{1}, {T}, Sacrifice a Servo: Create a 1/1 colorless Thopter artifact creature token with flying.
{T}, Sacrifice a Thopter: Create a 4/4 colorless Construct artifact creature token.

Shadowspear

Equipped creature gets +1/+1 and has trample and lifelink.
{1}: Permanents your opponents control lose hexproof and indestructible until end of turn.
Equip {2}

Inventors' Fair

At the beginning of your upkeep, if you control three or more artifacts, you gain 1 life.
{T}: Add {C}.
{4}, {T}, Sacrifice Inventors' Fair: Search your library for an artifact card, reveal it, put it into your hand, then shuffle. Activate only if you control three or more artifacts.

Gods' Eye, Gate to the Reikai

{T}: Add {C}.
When Gods' Eye is put into a graveyard from the battlefield, create a 1/1 colorless Spirit creature token.

Pithing Needle

As this artifact enters, choose a card name.
Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.