Ancient White Dragon
Gargantuan Dragon (chromatic), Chaotic EvilAC 20
HP 333 (18d20 + 144)
Speed 40 ft., burrow 40 ft., fly 80 ft., swim 40 ft.
STR
26 (+8)
Save +8
DEX
10 (+0)
Save +6
CON
26 (+8)
Save +8
INT
10 (+0)
Save +0
WIS
13 (+1)
Save +7
CHA
18 (+4)
Save +4
Saving Throws DEX +6, WIS +7
Skills Perception +13, Stealth +6
Immunities Cold
Senses Blindsight 60 ft., Darkvision 120 ft., Passive Perception 23
Languages Common, Draconic
CR 20
Traits
Ice Walk. The dragon can move across and climb icy surfaces without needing to make an ability check. Additionally, Difficult Terrain composed of ice or snow doesn't cost it extra movement.
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.
Rend. Melee Attack Roll: +14, reach 15 ft. Hit: 17 (2d8 + 8) Slashing damage plus 7 (2d6) Cold damage.
Cold Breath (Recharge 5+). con 22, each creature in a 90-foot Cone. Failure: 63 (14d8) Cold damage. Success: Half damage.
Legendary Actions
Freezing Burst. con 20, each creature in a 30-foot-radius Sphere centered on a point the dragon can see within 120 feet. Failure: 14 (4d6) Cold damage, and the target's Speed is 0 until the end of the target's next turn. Failure or Success: 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.