The new Founders' homeworld was located at secret coordinates deep in Dominion space in the Gamma Quadrant. The Great Link appeared to cover much of the planet's surface, leaving very little landmass.
The USS Defiant was guided by the Jem'Hadar to this planet in 2372, when the Founders forced Odo to return to the Link to face judgment for killing another Changeling. (DS9: "Broken Link") Odo again returned to the planet at the end of 2375, after the end of the Dominion War, to cure the morphogenic virus infecting the Link and convince them that the solids did not pose a threat to them. (DS9: "What You Leave Behind")
Background information Edit
With the first Founders' homeworld having been attacked in DS9 Season 3 installment "The Die is Cast", the possibility of depicting a new homeworld for the species in the third season finale, which Paramount insisted not be a cliff-hanger, was ruled out by the DS9 writing staff. "We knew that for just one episode, we couldn't justify building the sets for the Founders' planet," explained Robert Hewitt Wolfe. (Star Trek: Deep Space Nine Companion, p. 250)
The second Founder homeworld was planned out in sketches by John Eaves, dated September 1996. One of these illustrated the planet as being lush with forest land, also having crags in the distance, and ornate pillars towering over the greenery. Another of the sketches showed the Founders' homeworld much as it eventually appeared, with a rocky isle surrounded by the ocean-like Great Link. (Star Trek: Deep Space Nine Companion, pp. 356 & 355) Visual Effects Supervisor David Stipes was also instrumental in recreating the Founders' homeworld for "Broken Link". "It was incredibly complicated to do," he recalled. "The little island that they built, had a huge sunset cyc that went way around the set. It was a hundred feet long. It might have been even longer than that, because it covered three sides of the set." (Cinefantastique, Vol. 32, Nos. 4/5, pp. 89 & 90)
When the Founders' homeworld made a final reappearance in series finalé "What You Leave Behind", the task of recreating the planet again fell to David Stipes. The live-action portion of the footage, which featured new shots, was directed by Allan Kroeker, and involved a new island set as well as a cyclorama. (Cinefantastique, Vol. 32, Nos. 4/5, pp. 89, 91 & 90) The set was on Paramount Stage 7, and the island was made of fiberglass. (Star Trek: Deep Space Nine Companion, p. 714)
In the videogame Star Trek Online, the planet is named Empersa. In the mission "Tenebris Torquent", part of the "Victory is Life" expansion campaign, Elim Garak sets a Hur'q-luring transponder on the planet as a form of insurance against the Female Changeling and her loyalists in the Dominion. In the following mission "Home", players join a fleet led by Odo to defend Empersa first from space, and then fighting against the Hur'q swarms on the "shore" of the Great Link itself. Eventually, Julian Bashir is able to use the Ketracel-white aboard a Hur'q dreadnought to liberate the Hur'q from their savage ways and cause them to depart Empersa. The defense of Empersa from a Hur'q invasion is the last phase of the Gamma Quadrant Battlezone.