Champion of the Bird

• Desecrating Aura. Undead within a 30-foot radius of the nightwalker have advantage on attack rolls and saving throws. At the start of the nightwalkers turn, the nightwalker can choose any undead under the control of another spellcaster within range to make a DC 16 Charisma saving throw or go under the nightwalkers control. Additionally, when a creature dies in this radius, the nightwalker has resistance to the damage that killed it until the start of its next turn. If it already has resistance, it gain immunity. 
• Sunlight Weakness. While in sunlight, the nightwalker has disadvantage on attack rolls, ability checks, and saving throws.
• Innate Spellcasting. The nightwalker’s innate spellcasting ability is Intelligence (spell save DC 19). It can innately cast the following spells, requiring no material components.
• At will: contagion, darkness, dispel magic
• 3/day each: confusion, haste, invisibility, counterspell, create undead, shield
• 1/day each: cone of cold, finger of death, sending, tether essence, danse macabre, plane shift
• Adamantine Armor. Any critical hit against the nightwalker becomes a normal hit.
• War Eternal. When a creature dies within 30 ft. of the nightwalker, that creature is brought back at 1 hitpoint and must succeed on a DC 20 Wisdom saving throw or be charmed by the nightwalker. While charmed, it must attack the nearest creature that it has as an ally, with everything it has. (60%) A creature who is affected by this or passes the save cannot be brought back by this ability for 24 hours.
• Shadowy Immutable Form. The nightwalker is immune to any spell or effect that would alter its form. Additionally, the nightwalker cannot be forcibly moved by any spells.
• Unusual Nature. The nightwalker doesn’t require air, food, drink, or sleep.
• Eyes of Night. Magical darkness doesn’t impede the nightwalker’s darkvision.

• Multiattack. The nightwalker makes three attacks.
• Claw. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 25 (3d8 + 12) slashing damage plus 14 (4d6) cold damage.
• Army of Shadows (4 recharge). The nightwalker magically calls 2d4 shadows, provided that the nightwalker is not in bright light. The shadows arrive in one round, acting as allies of the nightwalker and obeying its commands. The shadows remain for 1 hour, until the nightwalker dies, or until the nightwalker dismisses them as a bonus action. The nightwalker may have a maximum of 6 at his command at all times.
• Drink Despair. (5 recharge)Ranged Magical Attack: 50 ft., DC19 Wisdom saving throw. The nightwalker sends a wave of dark energy in a cone deal damage equal to the creatures two times the creatures Charisma score + the number of conditions it afflicted by. It heal for half of the total damage it deals.

• Malevolent Presence (2/day). Any creature with an Intelligence of 4 or more that is within 30 feet of the nightwalker must succeed on a DC 19 Wisdom saving throw or be charmed by it for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the nightwalkers's Malevolent Presence for the next 24 hours. A creature charmed in this way fixates on another creature or object that the nightwalker mentally chooses and must, on each of its turns, move as close as it can to that target and use its action to make a melee attack against it. If the nightwalker doesn't choose a target, the charmed creature can act normally on its turn.

• Retreat to Shadows. As a reaction to taking damage, the nightwalker teleports to a patch of dark or dim light, expanding a use of his invisibility. 
• Legendary Resistance. The nightwalker automatically succeeds a save it would have otherwise failed. (4/day)

The nightwalker has 8 legendary actions.

Channel Negative Energy (Costs 3 Actions). The monster seeps with foul necrotic energy, channeling the negative energy plane. Each creature within 20 feet of the monster takes 18 (4d8) necrotic damage and only regains half its normal hit points from magical healing until the end of its next turn.

Spectral Force (Costs 3 Actions). The monster summons a force of spectral creatures that swirl around it. All creatures who start their turn within 30 feet of the monster succeed on a DC (19) Wisdom saving throw against this magic. On a failed save, a target can’t use reactions, its speed is halved, and it can’t make more than one attack on its turn. These spectral creatures last until the end of the monster’s next turn.

 Shield of Souls (Cost 2 Actions). The monster channels a powerful abjuring spell of necrotic energy. It gains 8d4 temporary hitpoints. While it has temporary hitpoints, it has resistant to all spell attacks and advantage on spell effects against it. When a creature targets it with a melee attack, it must make a DC 15 Constitution saving throw, or take necrotic damage equal to the current value of the temporary hitpoints. When the temporary hitpoints are completely, it keeps these effects until after the next time it is hit.