Succubus Form. When the incubus finishes a Long Rest, it can shape-shift into a Succubus, using that stat block instead of this one. Any equipment it is wearing or carrying isn't transformed.
Multiattack. The incubus makes two Restless Touch attacks.
Restless Touch. Melee Attack Roll: +7, reach 5 ft. Hit: 15 (3d6 + 5) Psychic damage, and the target is cursed for 24 hours or until the incubus dies. Until the curse ends, the target gains no benefit from finishing Short Rests.
Spellcasting. The incubus casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 15):
At Will: Disguise Self, EtherealnessNightmare (Recharge 6). Wisdom Saving Throw: DC 15, one creature the incubus can see within 60 feet. Failure: If the target has 20 Hit Points or fewer, it has the Unconscious condition for 1 hour, until it takes damage, or until a creature within 5 feet of it takes an action to wake it. Otherwise, the target takes 18 (4d8) Psychic damage.