Armor Class 18 (natural armor)
Hit Points 225 (18d12 + 108)
Speed 40 ft., fly 80 ft., climb 40 ft., burrow 30 ft.
Saving Throws DEX +7, CON +11, WIS +8, CHA +9
Skills History +9, Perception +13, Persuasion +14, Stealth +7
Damage Resistances lightning, thunder
Condition Immunities frightened
Senses blindsight 60 ft., darkvision 120 ft., passive Perception 23
Languages Common, Draconic, telepathy 120 ft.
Challenge 15
Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.
Spider Climb. The dragon can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Tunneler. The dragon can burrow through solid rock at half its burrowing speed and can leave a 10-foot-diameter tunnel in its wake.
Multiattack. The dragon makes one Bite attack and two Claw attacks.
Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 5 (1d10) thunder damage.
Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 6) slashing damage.
Debilitating Breath (Recharge 5–6). The dragon exhales a pulse of high-pitched, nearly inaudible sound in a 60-foot cone. Each creature in that area must make a DC 19 Constitution saving throw. On a failed save, the creature takes 44 (8d10) thunder damage and is incapacitated until the end of its next turn. On a successful save, the creature takes half as much damage and isn't incapacitated.
Change Shape. The dragon magically transforms into any creature that is Medium or Small, while retaining its game statistics (other than its size). This transformation ends if the dragon is reduced to 0 hit points or uses a bonus action to end it.
Psychic Step. The dragon magically teleports to an unoccupied space it can see within 60 feet of it.
Claw. The dragon makes one Claw attack.
Psionics (Costs 2 Actions). The dragon uses Psychic Step or Spellcasting.
Telekinetic Fling (Costs 3 Actions). The dragon chooses one Small or smaller object that isn't being worn or carried that it can see within 60 feet of it, and it magically hurls the object at a creature it can see within 60 feet of the object. The target must succeed on a DC 17 Dexterity saving throw or take 31 (9d6) bludgeoning damage.
Fizban's Treasury of Dragons, p. 215