Mana Rig

The Mana Rig was a complex of structures built by the Thran on the continent of Shiv.

Description
It was found by Urza during the events of Urza's Legacy. He managed to get the Goblins and Viashino to work together to operate the Rig. It produced "Thran metal" for the Skyship Weatherlight as well as a powerstone in which the mana from Serra's Realm would later be stored.

During the Phyrexian Invasion of Dominaria, the Mana Rig came under attack by Phyrexian forces who came to either claim it or, failing that, destroy it. However, to both Yawgmoth's minions and Urza's surprise, the seemingly defenceless structure launched a counterattack by deploying a detachable and mobile segment of itself that could shoot huge geysers of molten lava with deadly accuracy, a feature installed by Jhoira who had been in charge of the complex.

This section of the Mana Rig was left behind for Urza to use to continue forging Thran metal and Powerstones while the main part of the Rig along with Jhoira and a large portion of Shiv was phased out by Teferi along with Zhalfir until its return during the Time Spiral storyline.

It's unknown what became of the mobile part of the Mana Rig.

Circa 4560 AR
The Mana Rig was deemed too powerful for anyone to use by the Shivan Council, and left to sit idle. Gavon Deniz attempted to seize control of it, failed, and disappeared along with the Power Stone the rig was creating.

Other Mana Rigs
At at the time of the Thran there had been apparently more than one Mana Rig, another being at Halcyon in Terisiare.