Armor Class 18
Hit Points 184 (16d10 + 96)
Speed 20 ft., fly 30 ft.
Saving Throws CON +11, INT +9, WIS +6, CHA +7
Damage Resistances cold, fire, lightning
Damage Immunities poison
Condition Immunities frightened, poisoned
Senses Truesight 120 ft., passive Perception 11
Languages Abyssal; telepathy 120 ft.
Challenge 13
Demonic Restoration. If the nalfeshnee dies outside the Abyss, its body dissolves into ichor, and it gains a new body instantly, reviving with all its Hit Points somewhere in the Abyss.
Magic Resistance. The nalfeshnee has Advantage on saving throws against spells and other magical effects.
Multiattack. The nalfeshnee makes three Rend attacks.
Rend. m +10, reach 10 ft. Hit: 16 (2d10 + 5) Slashing damage plus 11 (2d10) Force damage.
Teleport. The nalfeshnee teleports up to 120 feet to an unoccupied space it can see.
Horror Nimbus (Recharge 5–6). wis DC 15, each creature in a 15-foot Emanation originating from the nalfeshnee. 28 (8d6) Psychic damage, and the target has the Frightened condition for 1 minute, until it takes damage, or until it ends its turn with the nalfeshnee out of line of sight. The target is immune to this nalfeshnee's Horror Nimbus for 24 hours.
Pursuit. Another creature the nalfeshnee can see ends its move within 120 feet of the nalfeshnee. The nalfeshnee uses Teleport, but its destination space must be within 10 feet of the triggering creature.
Monster Manual (2024), p. 224