Terminus

Terminus is one of the Throne Worlds - universes existing on a radically higher energy level than the much more common Vassal Worlds. As a result of this, Terminus simply doesn't play according to rules recognizable to inhabitants of more 'natural' planes of existence. In harsher words, it would be nonsensical - if it didn't follow its own rules.
In the far past, it was the homeworld - and seat of power - of Ahriman, one of the twelve Dark Lords. Ahriman was deposed following the Great Multiversal War, however his influence still permeats the entire plane, with every single detail of this universe once sculpted by his insane hands.

Geography

Terminus is one of the Throne Worlds that are least divergent from the 'normalcy' as understood by rules typical for the Old Earth - there is a spherical world, surrounding a star, and with a number of generally unimportant rocks spread throughout the system. However, that's where the normalcy pretty much ends. To begin with, the star is entirely black - and while it does project some light, the Terminus is rather dark even at noon. And if that wasn't enough, the light of the Black Sun is deadly.
Exposure of the Black Sun slowly drains life from your body, making you weaker and weaker until your heart no longer has any energy left to beat. Then, after a while, your body starts to moving again - after all, Terminus is a world of the undead, most of which appear to worship the Black Sun as their progenitor. The difference between the Terminus now and Terminus before System was introduced, was that now you tend to maintain your pre-transformation mind if you how to do that, instead of becoming a mindless puppet of Ahriman.
As one can expect, the surface is desolate. No plantlife. Landscape composed of either rocky wasteland (with rocks darkened by the Black Sun's light) or deserts of pale sand, that remains could to touch even if brought elsewhere and heated. Everything that moves is almost certainly an undead (animalistic and aggressive, or sapient and dangerously human). In short, one of the least nice places in the multiverse. There is also the fact that large swathes of this world are still irradiated after the human conquest of Terminus during the Great Multiversal War.
There are cities and fortresses tucked here and there, some a leftover from Ahriman's times and some built later on (and mostly inhabited by the local sapient undead). The most interesting feature is probably the Glowing Sea - hundred kilometers wide basin filled with glowing water. It's actually what remains from Ahriman's citadel after Mankind has unleashed so much firepower upon it that it (and everything near it) melted down. The liquid is still warm to touch - and, due to how many nuclear weapons were employed during the assault, extremely radioactive. Some undead sometimes dive to the depths of it, to the sunken part of Ahriman's fortress (and either not return at all or return with fabulous treasures).