1 - This entire area is accessible by leaving the Planar Sphere after you've activated it (by flipping the switch in the first room). After speaking to Lavok in the Navigation Room, he'll explain that you need to power up the Planar Sphere by bringing the heart of a Demon to the Planar Sphere core. The heart can be found as loot off a Tanar'ri in the dead center of this netherworld.