Adult Cosmic Dragon

Cosmic. The dragon can breathe air and water, and in space. Can

Legendary Resistance (3/Day, or 6/Day in Lair). If the dragon fails a saving throw, it can choose to succeed instead.

Multiattack. The dragon makes a Rend attack, a Bite attack. It can replace one attack with a use of Spellcasting to cast Ice Knife (level 3 version).

Rend. Melee Attack Roll: +11, reach 10 ft. Hit: 13 (2d6 + 6) Slashing damage plus 4 (1d8) Fire damage.

Cosmic Breath (Recharge 4–6). Dexterity Saving Throw: DC 18, each creature in a 60-foot-long, 5-foot-wide Line. Failure: 54 (12d8) Radiant damage. Success: Half damage.

Spellcasting. The dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 19, +9 to hit with spell attacks):

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 18 (2d10 + 7) piercing damage plus 5 (1d10) fire damage.

Claw. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 7) slashing damage.

Tail. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 16 (2d8 + 7) bludgeoning damage.

At Will: Detect Magic, Dimension Door, Ice Knife (level 3 version)

1/Day Each: Imprisonment, True Resurrection

Legendary Action Uses: 3 (4 in Lair). Immediately after another creature's turn , the dragon can expend a use to take one of the following actions. The dragon regains all expended uses at the start of each its turns.

Cosmic Cloud. 10Dexterity Saving Throw: DC 17, one creature the dragon can see within 120 feet. Failure: 22 (4d10) Psychic damage, and the target has Disadvantage on saving throws to maintain Concentration until the end of its next turn. Failure or Success: The dragon can’t take this action again until the start of its next turn.

Frightful Presence. The dragon uses Spellcasting to cast Fear. The dragon can’t take this action again until the start of its next turn.

Beam. The dragon can use its breath weapon twice in a row