CR 3 (700 XP) Medium monstrosity (shadow), neutral evil
Special traits: Maybe Invisibility in darkness, or some kind of shadow teleport. Actions: Multiattack with claws, maybe a shadow breath or something. Legendary actions? If CR is 4, maybe 3-4 legendary actions. Companion of Darkness -Ch. 9- By Berkili4
14 (natural armor) HP 65 (10d8 + 30) Speed 30 ft., climb 20 ft. CR 3 (700 XP) Medium monstrosity (shadow), neutral