Ancient Red Dragon

Gargantuan Dragon, chaotic evil

AC: 22 (natural armor)
HP: 507 (26d20 + 234)
Speed: 40 ft., fly 80 ft., climb 40 ft.

STR	DEX	CON	INT	WIS	CHA
30 (+10)	10 (+0)	29 (+9)	18 (+4)	15 (+2)	27 (+8)

Saves: Str +10, Dex +7, Con +9, Int +4, Wis +9, Cha +8
Skills: Perception +16, Stealth +7
Immunities: fire
Senses: blindsight 60 ft., darkvision 120 ft., passive Perception 26
Languages: Common, Draconic
CR: 24 (XP 62,000)

Traits

Legendary Resistance (4/Day, or 5/Day in Lair).

If the dragon fails a saving throw, it can choose to succeed instead.

Actions

Multiattack.

The dragon makes three Rend attacks. It can replace one attack with a use of Spellcasting to cast Scorching Ray (level 3 version).

Rend.

Melee Attack Roll: +17, reach 15 ft. 19 (2d8 + 10) Slashing damage plus 10 (3d6) Fire damage.

Fire Breath.

Dexterity Saving Throw: DC 24, each creature in a 90-foot Cone. Failure: 91 (26d6) Fire 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 23, +15 to hit with spell attacks):

At Will: Command, Detect Magic, Scorching Ray
1/Day Each: Fireball, Scrying

Legendary Actions

Commanding Presence.

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.

Fiery Rays.

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.

Pounce.

The dragon moves up to half its Speed, and it makes one Rend attack.