Urza's Power Plant

{T}: Add {C}. If you control an Urza's Mine and an Urza's Tower, add {C}{C} instead.

Urza's Tower

{T}: Add {C}. If you control an Urza's Mine and an Urza's Power-Plant, add {C}{C}{C} instead.

Sol Ring

Guardian Beast

As long as Guardian Beast is untapped, noncreature artifacts you control can't be enchanted, they have indestructible, and other players can't gain control of them. This effect doesn't remove Auras already attached to those artifacts.

Candelabra of Tawnos

Artifact Possession

Enchant artifact
Whenever enchanted artifact becomes tapped or a player activates an ability of enchanted artifact without {T} in its activation cost, Artifact Possession deals 2 damage to that artifact's controller.

Dragon Engine

{2}: Dragon Engine gets +1/+0 until end of turn.

Urza's Mine

{T}: Add {C}. If you control an Urza's Power-Plant and an Urza's Tower, add {C}{C} instead.

Amulet of Kroog

{2}, {T}: Prevent the next 1 damage that would be dealt to any target this turn.

Phyrexian Gremlins

You may choose not to untap Phyrexian Gremlins during your untap step.
{T}: Tap target artifact. It doesn't untap during its controller's untap step for as long as Phyrexian Gremlins remains tapped.

Ornithopter

Jade Statue

{2}: Jade Statue becomes a 3/6 Golem artifact creature until end of combat. Activate only during combat.

Clockwork Beast

Clockwork Beast enters the battlefield with seven +1/+0 counters on it.
At end of combat, if Clockwork Beast attacked or blocked this combat, remove a +1/+0 counter from it.
{X}, {T}: Put up to X +1/+0 counters on Clockwork Beast. This ability can't cause the total number of +1/+0 counters on Clockwork Beast to be greater than seven. Activate only during your upkeep.

Bazaar of Baghdad

{T}: Draw two cards, then discard three cards.

Howl from Beyond

Target creature gets +X/+0 until end of turn.

Mishra's Workshop

{T}: Add {C}{C}{C}. Spend this mana only to cast artifact spells.

Swamp

Strip Mine

{T}: Add {C}.
{T}, Sacrifice Strip Mine: Destroy target land.

Gate to Phyrexia

Sacrifice a creature: Destroy target artifact. Activate only during your upkeep and only once each turn.

Golgothian Sylex

{1}, {T}: Each nontoken permanent with a name originally printed in the Antiquities expansion is sacrificed by its controller.

Rocket Launcher

{2}: Rocket Launcher deals 1 damage to any target. Destroy Rocket Launcher at the beginning of the next end step. Activate only if you've controlled Rocket Launcher continuously since the beginning of your most recent turn.

Priest of Yawgmoth

{T}, Sacrifice an artifact: Add an amount of {B} equal to the sacrificed artifact's mana value.

Library of Leng

You have no maximum hand size.
If an effect causes you to discard a card, discard it, but you may put it on top of your library instead of into your graveyard.

Tetravus

Flying
Tetravus enters the battlefield with three +1/+1 counters on it.
At the beginning of your upkeep, you may remove any number of +1/+1 counters from Tetravus. If you do, create that many 1/1 colorless Tetravite artifact creature tokens. They each have flying and "This creature can't be enchanted."
At the beginning of your upkeep, you may exile any number of tokens created with Tetravus. If you do, put that many +1/+1 counters on Tetravus.

Oubliette

When Oubliette enters the battlefield, target creature phases out until Oubliette leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)