: Add 
. If you control an Urza's Mine and an Urza's Power-Plant, add Urza's Tower is one piece of the three-land mana engine commonly called Tron. On its own, it taps for one colorless mana. When you also control Urza's Mine and Urza's Power Plant, it produces 3 colorless mana instead. The complete set produces seven mana from three lands, creating a major jump in available resources for expensive artifacts and colorless threats.
Expedition Map helps find a missing piece, making the land package more consistent. Sylvan Scrying offers another search option in decks with green, while Ancient Stirrings can find colorless cards among the top five cards of the library. These support cards matter because drawing only one or two different pieces does not unlock the increased output.
Karn Liberated, Wurmcoil Engine, and large Eldrazi illustrate the kinds of threats that can use the assembled mana efficiently. The engine produces colorless rather than colored mana, so a hand full of demanding colored costs may still be difficult to cast. Build the payoff package and the rest of the mana base with that distinction in mind.
In singleton formats, assembling all three different lands is less consistent than in decks allowed multiple copies. Include the package when land tutors and colorless payoffs justify the slots. Land destruction aimed at one piece also switches the others back to their ordinary output, so consider recovery effects or alternative acceleration rather than making the entire deck depend on keeping the trio intact.
