This article might have further canon details available on.
The Negative Energy Plane, sometimes referred to as the Void, is the source of negative energy, which destroys life and provides undead creatures with power and unlife. The dark twin of the Positive Energy Plane, it is a place of annihilation and destruction, leaching life energy from all who visit it.12
The Negative Energy Plane is a nearly infinite and largely empty sea of darkness and entropy that can easily be mistaken for space on the Material Plane, with a crucial difference: the Void actively breaks down matter and kills living creatures within it. At its edge is a shore of cliffs that continuously erode and renew, and glow a sickly silver; scholars speculate that this light is reflected from the Positive Energy Plane or comes from souls that died in the Negative Energy Plane. Continent-sized slabs sometimes break away to drift through the Void, and appear as flickering stars in the sky. Those who can withstand the entropy reside on these pieces of solid ground until they inevitably break down; only the strongest magic or technology can create permanent fixtures on the Negative Energy Plane.1
Occasionally, on entropy-soaked rocks, pure negative energy coalesces into crystalline deposits called blight quartz, a black or dark grey stone that flashes with dark purple energy and lacks normal minerals' molecular composition.1
Some of the Negative Energy Plane's few truly native creatures are sceaduinars, crystalline outsiders with an innate hatred of those born of positive energy, and kavearins, deposits of blight quartz that spontaneously became sentient.13
The most populous of the Negative Energy Plane's inhabitants are undead that fly through the void, impervious to the entropy. Starships travelling through the Negative Energy Plane must take special precautions to prevent incorporeal undead, most commonly oblivion shades, from passing through the hull to attack crew or instruments. In particular, the Corpse Fleet has built a series of ports on a cluster of drifting rocks, though due to the Negative Energy Plane's entropy, ships are only moored here briefly when taking refuge from Pact Worlds authorities. Intelligence reveals that the Corpse Fleet and the sceaduinars are frequently in contact, despite the latter's hatred for undead, leading the Pact Worlds government to increase the monitoring for a potential alliance and attack.3
Living creatures that survive an overwhelming dose of negative energy or long-term exposure to the Negative Energy Plane can find themselves transformed into void-ravaged creatures, undead-like (but still living) creatures that cannot exist long outside of the Negative Energy Plane.1