Avatar of Justice

Angelic Weapons. The avatar's weapon attacks are magical. When the avatar hits with any weapon, the weapon deals an extra 6d8 radiant damage (included in the attack).

Divine Awareness. The avatar knows if it hears a lie.

Innate Spellcasting. The avatar's spellcasting ability is Wisdom (spell save DC 25). It can innately cast the following spells, requiring no material components:

At will: detect evil and good, detect thoughts, plane shift

3/day each: blade barrier, dispel evil and good, resurrection

1/day each: commune, control weather

Magic Resistance. The avatar has advantage on saving throws against spells and other magical effects.

Innocent Until Proven Guilty. The avatar cannot harm a creature until it has used its Resounding Edict ability against it and it was an evil or neutral creature.

Celestial Bound. If the avatar drops to 0 hit points on any plane other than the Celestial Planes, then it reappears on Mount Celestia in a crippled state and must recover. 

Legendary Resistance (3/Day). If the avatar fails a saving throw, it can choose to succeed instead. 

Inscrutable. Magic like the detect thoughts spell cannot determine what the avatar is thinking.

Divine Nature. The avatar does not require eat, drink, or sleep.

Multiattack. The avatar makes two greatgavel attacks.

Greatgavel. Melee Weapon Attack: +15 to hit, reach 5 ft., one target. Hit: 22 (4d6 + 8) force damage plus 27 (6d8) radiant damage.

Bolt of Radiance. Ranged Spell Attack: +13 to hit, range 150/600 ft., one target. Hit: 15 (2d8 + 6) radiant damage plus 27 (6d8) radiant damage. All attacks against this creature do double damage until the start of the avatar's next turn.

Resounding Edict (Recharge 6). The avatar picks one creature it can see within 300 feet of it. If the creature's alignment is good, then the creature gains 100 temporary hit points. If the creature is evil, the creature must make a DC 25 Wisdom saving throw. On a fail, the creature takes 95 (10d10) thunder damage plus 95 (10d10) psychic damage and is stunned until the end of the avatar's next turn. On a success the creature takes half as much damage and isn't stunned. Nothing happens to a true neutral, chaotic neutral, or lawful neutral creature. Once the avatar has used this ability on a creature, the avatar cannot use this ability on that creature again until the next dawn.

Chains of the Law (3/day). The avatar magically summons silver chains to bind an enemy. One creature within 120 feet of the avatar must succeed on a DC 25 Strength or Dexterity check or be restrained for 1 hour. At the end of the hour, the bound creature can retake the saving throw with disadvantage. While the creature is restrained in this way, the avatar can move the creature 40 feet in any direction it chooses using a bonus action.

Radiant Height. The avatar can change its size to huge or gargantuan. Its statistics are the same in each form and it can use another bonus action to return to the large size.

Retaliatory Judgement. If a creature with an evil alignment hits the avatar with an attack, the avatar immediately recharges its Resounding Edict feature.

The avatar can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The avatar regains spent legendary actions at the start of its turn.

Rush of Judgement. The avatar moves up to its movement speed and can move through other creatures' space. If the avatar moves through another creatures space, then that creature must succeed on a DC 23 Dexterity saving throw or be pushed 30 feet out of the way and take 30 (4d12) force damage and be knocked prone. On a success the creature is pushed 10 ft out of the way and only takes half as much damage.

Radiant Wave (Costs 2 Actions). The avatar emits magical, divine energy. Each creature of its choice in a 10-foot radius must make a DC 23 Dexterity saving throw, taking 14 (4d6) fire damage plus 14 (4d6) radiant damage on a failed save, or half as much damage on a successful one.

Fearful Form (Costs 3 Actions). The avatar targets one creature it can see within 30 feet of it. If the target can see it, the target must succeed on a DC 15 Constitution saving throw or be frightened until magic such as the calm emotions spell removes the frightened condition.