Mishra's Factory

{T}: Add {C}.
{1}: This land 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.

Mishra's Workshop

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

Strip Mine

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

Urza's Construction Drone

Urza's Tower

Urza's Mine

Urza's Power Plant

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

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

Antiquities