Tectonic Edge

{T}: Add {C}.
{1}, {T}, Sacrifice Tectonic Edge: Destroy target nonbasic land. Activate only if an opponent controls four or more lands.

Sea Gate Wreckage

{T}: Add {C}. ({C} represents colorless mana.)
{2}{C}, {T}: Draw a card. Activate only if you have no cards in hand.

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.

Ruins of Oran-Rief

Ruins of Oran-Rief enters tapped.
{T}: Add {C}. ({C} represents colorless mana.)
{T}: Put a +1/+1 counter on target colorless creature that entered this turn.

Urza's Tower

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

Shrine of the Forsaken Gods

{T}: Add {C}.
{T}: Add {C}{C}. Spend this mana only to cast colorless spells. Activate only if you control seven or more lands.

Urza's Factory

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

Urza's Power Plant

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

Foundry of the Consuls

{T}: Add {C}.
{5}, {T}, Sacrifice Foundry of the Consuls: Create two 1/1 colorless Thopter artifact creature tokens with flying.

Urza's Mine

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

Marvin, Murderous Mimic

Marvin, Murderous Mimic has all activated abilities of creatures you control that don't have the same name as this creature.

Wastes

Spawning Bed

{T}: Add {C}.
{6}, {T}, Sacrifice Spawning Bed: Create three 1/1 colorless Eldrazi Scion creature tokens. They have "Sacrifice this creature: Add {C}."

Sequestered Stash

{T}: Add {C}.
{4}, {T}, Sacrifice Sequestered Stash: Mill five cards. Then you may put an artifact card from your graveyard on top of your library.