Gargantuan Dragon (Chromatic), Chaotic Evil
Armor Class 22 Initiative +14 (24) Hit Points 507 (26d20 + 234) Speed 40 ft., Climb 40 ft., Fly 80 ft.
Saving Throws Str +10, Dex +7, Con +9, Int +4, Wis +9, Cha +8
Skills Perception +16, Stealth +7
Damage Immunities Fire
Senses Blindsight 60 ft., Darkvision 120 ft.; Passive Perception 26
Languages Common, Draconic
Challenge Rating 24
If the dragon fails a saving throw, it can choose to succeed instead.
The dragon makes three Rend attacks. It can replace one attack with a use of Spellcasting to cast Scorching Ray (level 3 version).
Melee Attack Roll: +17, reach 15 ft. Hit: 19 (2d8 + 10) Slashing damage plus 10 (3d6) Fire damage.
Dexterity Saving Throw: DC 24, each creature in a 90-foot Cone. Failure: 91 (26d6) Fire damage. Success: Half damage.
The dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 23, +15 to hit with spell attacks):
At Will: Command (level 2 version), Detect Magic, Scorching Ray (level 3 version)
1/Day Each: Fireball (level 6 version), Scrying
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 of its turns.
The dragon uses Spellcasting to cast Command (level 2 version). The dragon can't take this action again until the start of its next turn.
The dragon uses Spellcasting to cast Scorching Ray (level 3 version). The dragon can't take this action again until the start of its next turn.
The dragon moves up to half its Speed, and it makes one Rend attack.