Re dell'Incubo, the King of Nightmares, inhabits Nightmare Land—a forbidden dimension of dark depths and terror accessed through a dragon-marked door in Slumberland. This realm pulses with crimson palpitations symbolizing nightmare's core, populated by shapeshifting Boomps and monstrous minions under his command. His oppressive presence embodies Nightmare Land's essence. Imprisoned behind the sealed door, his release occurs when a young visitor, manipulated by the trickster Flip, ignores warnings and unlocks it with a universal key. Freed, Re dell'Incubo immediately abducts King Morpheus during Slumberland's coronation, plunging the realm into chaos and cementing himself as a usurping force. Post-escape, he fortifies Nightmare Land into a stronghold guarded by menacing creatures. Demonstrating strategic aggression, he deploys gigantic bats to ambush and capture Morpheus's daughter, her companion, and allies attempting a rescue. These captives join Morpheus in Nightmare Castle, where Re dell'Incubo confronts them directly. In the confrontation, he demands Slumberland's royal scepter—the sole weapon opposing him—threatening hostages to force compliance. During the ensuing battle, his formidable power necessitates the scepter's full incantation to defeat him. Activated by the young visitor, the scepter destroys Re dell'Incubo and purifies Nightmare Land, seemingly at fatal cost to the wielder. He represents the primordial threat of nightmares given form—a force of corruption and captivity vanquished by courage and Slumberland's ancient magic.