Foundation Prime is a world in LEGO Dimensions that Lord Vortech. uses as his main base and is also where all the Foundation Elements of the franchises were created including the Green Baseplate. It is one of the major worlds in Lego Dimensions 2: The Rise of Enoch where it is the homeworld of Foundation Crime and the Foundation Entities. It also serves as the origin points of the Foundation Gauntlet and the Temple of Foundation.
Foundation Prime is a world that existed at the start of time and was where all of the foundation elements were created before being used to build the other dimensions. It also contains the original Green Baseplate which is the foundation of all dimensions. Foundation Prime is highly unstable with bricks erupting from the surface constantly.
Foundation Prime is first seen in the Prologue when Lord Vortech and X-PO arrive, X-PO finds the origin of the Foundation Elements and is then banished by Vortech. Lord Vortech uses his powers to assemble a fortress surrounding the origin point. From this point forward Vortech uses Foundation prime as his home base from which he captures heroes and good guys and sends villains and bad guys to carry out his takeover of all the dimensions by returning the foundation elements to their point of origin. In Prime Time Vortech uses his powers to assemble obstacles to stop Batman, Gandalf, and Wyldstyle from reaching his fortress but they do finally arrive and fight Vortech to save their friends. However, their attempts to banish Vortech fail and the villains collect the final Foundation Elements from Vorton revealing the Green Baseplate which Vortech uses to assemble The Tri from Robin, Frodo, and MetalBeard. The Heroes return to a final fight with Vortech during The Final Dimension.
Grand Emperor Enoch and Karnia went to Foundation Prime to seek help from Foundation Crime. They accept and show him the visions of Lord Vortech and the Tri. Enoch, Karnia and Foundation Crime then broke into the Temple of Foundation and stole the Foundation Gauntlet from it's pedestal.
Andy Starheart and his friends later went to Foundation Prime to find the gauntlet but were too late, realizing it's gone. The heroes go deeper inside the temple, fight Azog and look into the Fountain of Foundation to look into the future of the Multiverse. This caused Andy to go back home and defeat his longtime bully Rafael Darkstrom.
After Enoch's ultimate defeat, Andy went back to Foundation Prime to return the gauntlet back where it belongs.
In the post-credits scene, Foundation Crime's new leader Evilina kneels to an entity similar to Lord Vortech(offscreen) and tells him that it's almost time.