* CompleteMonster: ArchEnemy Cobweb is a demon that invades the minds of humans and drives them insane with his lies, all while plotting to invade and enslave the Earth, framing Sleepwalker in the process. Cobweb turned people against Sleepwalker, while corrupting their minds, all the while using invading forces to wreak havoc and devour innocents' minds. Cobweb planned to have Sleepwalker's host, Rick sheridan cross the DespairEventHorizon and betray Sleepwalker, which would allow Cobweb to turn Rick into a portal to Earth and wreak destruction there. Since the denizens of the Mindscape don't need to devour people's minds to survive, Cobweb stands out as a monster amongst his own species.
* NightmareFuel: Sleepwalker suffers a series of mind-bending hallucinations when he becomes exposed to a certain frequency of light.
** The more terrifying part is when warp beams are used on living things. It's no wonder he's under the oath not to do just that.