Asterian

False Appearance. While the Asterian remains motionless, it is indistinguishable from a normal suit of armor.

Ethereal Sight. Asterian can see 60 feet into the Ethereal Plane when it is on the Material Plane, and vice versa.

Crown of Withered Flowers. If Asterian's crown of withered flowers is destroyed (HP: 1 the crown of flowers will be hit if the player hits Asterians head), Asterian becomes enraged and gains Immunity to Bludgeoning, Piercing, and Slashing damage from non-magical weapons and Resistance to Bludgeoning, Piercing, and Slashing damage from magical weapons. Asterian also becomes able to use his legendary actions. A 20ft long ethereal blade overlaps with Asterians Longsword giving him reach out to 20ft 

Multiattack. Asterian makes two greatsword attacks.

Greatsword. Melee Weapon Attack: +11 to hit, reach 10 ft (20ft )., one target. Hit: 19 (4d6 + 7) slashing damage.

Shield. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 20 [rollable](3d8 + 7);

Shield Charge. Asterian moves up to 30 feet in a straight line and can move through the space of any creature smaller than himself. The first time it enters a creature’s space during this move, it makes a shield attack against that creature. If the attack hits, the target must also succeed on a DC 16 Strength saving throw or be pushed ahead of the giant for the rest of this move. If a creature fails the save by 5 or more, it is also knocked prone and takes 18 (3d6+7) bludgeoning damage, or 22 (4d6+7) bludgeoning damage if it was already prone.

Can only use legendary actions after the Crown of Withered flowers is destroyed.

The Asterian 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 Asterian regains spent legendary actions at the start of its turn.

Stomp. Asterian slams the ground, every creature and lose objects within 10ft must make a DC 16 Strength saving throw or be pushed away from him to 20ft and knocked prone.

Side Slash (Cost 2 Actions). Asterian slashes horizontally in a 20ft cone. Each creature within that area must make a DC 17 Dexterity saving throw taking 10 (3d6) psychic damage and 10 (3d6) slashing damage and is knocked prone on a failed save, or half as much damage on a successful one.

Vertical Slash (Cost 3 Actions). Asterian targets a creature slashes down onto them and the ground in a 20ft line the target creature will take 10 (3d6) psychic damage and 10 (3d6) slashing damaged and knocked prone on a failed save, or half as much damage on a successful one, and each creature horizontally within 20ft on each side to the longsword takes 21(6d6) psychic on a failed save, or half as much damage on a successful one. As ethereal swords, penetrate up from below the ground.