Urza's Cave

{T}: Add {C}.
{3}, {T}, Sacrifice Urza's Cave: Search your library for a land card, put it onto the battlefield tapped, then shuffle.

Urza's Mine

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

Urza's Power Plant

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

Urza, Prince of Kroog

Artifact creatures you control get +2/+2.
{6}: Create a token that's a copy of target artifact you control, except it's a 1/1 Soldier creature in addition to its other types.

Threefold Thunderhulk

Threefold Thunderhulk enters with three +1/+1 counters on it.
Whenever Threefold Thunderhulk enters or attacks, create a number of 1/1 colorless Gnome artifact creature tokens equal to its power.
{2}, Sacrifice another artifact: Put a +1/+1 counter on Threefold Thunderhulk.

Seat of the Synod

Chief of the Foundry

Other artifact creatures you control get +1/+1.

Palladium Myr

Steel Overseer

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

Illustrious Wanderglyph

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
Other artifact creatures you control get +2/+2 as long as you have the city's blessing.
At the beginning of each upkeep, create a 1/1 colorless Gnome artifact creature token.

Platoon Dispenser

At the beginning of your end step, if you control two or more other creatures, draw a card.
{3}{W}: Create a 1/1 colorless Soldier artifact creature token.
Unearth {2}{W}{W}

Gold Myr

Silver Myr

Urza's Tower

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

Razortide Bridge

Razortide Bridge enters tapped.
Indestructible
{T}: Add {W} or {U}.

Darksteel Citadel

Expedition Map

{2}, {T}, Sacrifice Expedition Map: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Urza's Workshop

{T}: Add {C}.
Metalcraft — {T}: Add {C} for each Urza's land you control. Activate only if you control three or more artifacts.

All Is Dust

Each player sacrifices all permanents they control that are one or more colors.

Urza's Factory

{T}: Add {C}.
{7}, {T}: Create a 2/2 colorless Assembly-Worker artifact creature token.