A concept sketch showing a bit of Vozirax's lair, Vighdura'ahl, the City of Endless Night

Affected by Vozirax's magic, the entire region around and inside the city is under a dense shadow aura, and the closer you get to the walls of the old dwarven fortress, the denser this aura becomes, dousing all flames and and magical lights. This aura is so strong inside the city, that even creatures with eyes adapted to the darkness are left completely blind without Vozirax's Blood Seal.

Vozirax, on the other hand, not only has other more accurate senses than his sight to rely on, but he also feels the disturbances in the shadows that envelop his domain, being able to pinpoint with astonishing accuracy every single creature within the gray ruined walls of Vighdura'ahl.

Doesn't matter where you go in his lair, you're always under the watch of the blind eyes of the pale king.