Cosmic Dragon

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

Cosmic Power (Mythic Trait; Recharges after a Short or Long Rest). If the dragon is reduced to 0 hit points, it doesn’t die or fall unconscious. Instead, it regains 300 hit points. In addition, the dragons scale armor is torn off, revealing the raw cosmic body underneath giving it access to mythic actions but reducing its Armor Class to 20 and losing immunity to fire while active.

Multiattack. The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 14 (4d6) fire damage.

Claw. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 17 (2d6 + 10) slashing damage.

Tail. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage.

Frightful Presence. Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 21 Wisdom saving throw or become frightened 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 dragon's Frightful Presence for the next 24 hours.

Cosmic Breath (Recharge 5–6). The dragon exhales cosmic power in a 90-foot cone. Each creature in that area must make a DC 24 Dexterity saving throw, taking 45 (13d6) radiant damage plus 45 (13d6) force damage on a failed save, or half as much damage on a successful one.

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

Detect. The dragon makes a Wisdom (Perception) check.

Tail Attack. The dragon makes a tail attack.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 25 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

If the Cosmic Dragon's mythic trait is active, it can use the options below as legendary actions for one hour after using Cosmic Power.

Swipe. The dragon makes two claw attacks.

Endless Void (Costs 2 Actions). The dragon recharges its breath weapon and uses it.

Supernova (Costs 3 Actions). Each creature within 100 feet of the dragon must succeed on a DC 21 Strength saving throw, or the creature takes 18 (3d12) force damage and 18 (3d12) radiant damage and they are knocked prone. If they succeed they only take half damage and are not knocked prone. Several portals to the Astral Plane rip open in the affected area and linger there until closed or the Cosmic Dragon dies. On turn 20 in combat, roll 1d4 and that many Berbalang fly throuugh the portals and attack anything in sight or the Dm's discretion.