The spider-shaped cosmology of Nir.
The head area is the material plane, with the shadow and ethereal planes overlapping it. The eight eyes are the inner planes: the four elemental planes and the four energy planes. The four energy planes are the negative, positive, anarchic, and axiomatic energy planes.
The abdomen is a realm called Afterlife. Afterlife is effectively the underworld, where all people go when they die. Depending on how a person acted in life is how they are treated here. However, not everybody goes here after they die. Some special individuals are taken out of the Afterlife by their deity and taken to one of the outer planes, sometimes to become petitioners, and sometimes for other reasons. A small branch (that does not tie in directly with the araneid cosmology) of Afterlife is called Afterdeath, which is for those who avoided death through necromantic practices (normally liches, vampires, etc.). Take note that Diemetheus, judge of the dead takes pity on those who were forced into undeath and does not torture them in Afterdeath. Afterdeath is the worst area of Afterlife.
Then there are the eight legs. Each leg connects to another outer plane. These planes include Elysium, Heaven, Hell, Abyss, Arborea, Utopia, and the Beastlands. Those are the seven planes, for near the end of the Aeon of Black Ice, the eighth leg, Gehenna, was destroyed. The planes are not the exact same as they were in the Manual of the Planes, however. Elysium is similar, though it has no desert plane. Celestia is not a mountain, but a series of clouds with great lands built upon them. Hell has the same structure, for the most part, but some of the planes have different climates and they all have different leaders. The Abyss is also very similar. Arborea has changed a bit, and will include a level for the Seelie courts, and is neutral. Utopia is the land of reason and greatness, and more lawfully aligned. The Beastlands are near identical to the Manual of the Planes version. Gehenna (which has nearly finished regrowing) will be a combination of gehenna and hades from the Manual of the Planes.
There will also be a lot of other planes and demiplanes not connected directly to Nir (the araneid) such as the Plane of Dreams, the Temporal Energy Plane, the Great Citadel & the Slaughterlands (for good and evil warriors, respectively), the Councilroom (meeting place of the gods), and the Elemental Plane of Sound (sub-energy plane). Those are just a few of the possible planes.