The Nightmare Planet is the counterpart planet of the Planet Dreamstone, though it does appear sentient like the former, , it pocesses The Nightmare Stone, thanks to Urpgor in it's first debut episode, The Return, it spoke in Deep Demonic Voice.
Nightmare Planet is voiced by Stuart Lock
The planet itself can be considered as the sister planet to The Red Planet of Doom, as both planets pocess similar powers. It's surface consists mainly of dark red baron canyons.
According to Zordrak it possesses dark powers, as he intends to take The Dreamstone there to corrupt it's energy into evil and use on himself.