Uranus

Uranus is an uninhabitable ice giant whose real prize is the Elysian Gate, a Dark Age warp-door that skips Sol's Mandeville points. Dorn made the region his Second Sphere; Perturabo stormed the gate in the Solar War and held it until the Scouring. Ten millennia later Indomitus Fleet Quintus mustered here and lost ships when the Embrace of Fire cooked off over the cloud-tops.