Dex +6, Con +6 Skills Stealth +6, Perception +4 Damage Resistances nonmagical physical Condition Immunities frightened, charmed Senses darkvision 60 ft., passive Perception 14 Languages understands Common but can't speak Challenge 3 (700 XP) Special Traits Invisibility. The companion is automatically invisible in areas of dim light or darkness. Shadow Form. The companion has advantage on Dexterity saving throws against nonmagical attacks and effects. Additionally, creatures have disadvantage on Wisdom (Perception) checks to detect it. Actions Multiattack. The companion makes two Shadow Claws attacks or one Shadowblast .
Special Traits: Maybe "Shadow Form": advantage on Dexterity saves against non-magical attacks, disadvantage on Perception checks to detect it. "Invisibility": automatically Invisible in dim light or darkness. Legendary Actions: 3-4 actions like telepathic bond with master, shadow surge attack, or teleport. Alternatively, since CR is 3, maybe 2-3 legendary actions. Companion of Darkness -Ch. 9- By Berkili4
Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3 + 1d6) piercing and necrotic damage. Dex +6, Con +6 Skills Stealth +6, Perception