Dragon, White Wyrm (CR 18)

Gargantuan Dragon (Cold)
Alignment: Always Chaotic Evil
Initiative: +0; Senses: blindsense 60 ft., darkvision120 ft., low-light vision, and keen senses
Languages: Draconic

AC: 38 (-4 size, +32 natural), touch 6, flat-footed 38
Hit Dice: 33d12+231 (445 hp); DR: 20/magic
Fort +25, Ref +18, Will +20
Speed: 60 ft., fly 250 ft. (poor), swim 60 ft., burrow 30 ft.
Space: 20 ft./15 ft. (20 ft. with bite)
Base Attack +33; Grapple +57
Attack: 1 Bite +41, 2 claws +36, 2 wings +36, 1 Tail Slap +36, 1 crush +36, 1 Tail sweep +36 melee; Breath +41 ranged
Damage: 1 bite 4d6+12, 2 claws 2d8+6, 2 wings 2d6+6, 1 tail slap 2d8+18, 1 crush 4d6+18, 1 tail sweep 2d6+18, Breath weapon 22d6 (33)
Special Attacks/Actions: Breath weapon, fear (DC 29), SR 25
Abilities: Str 35, Dex 10, Con 25, Int 14, Wis 15, Cha 16
Special Qualities: Cold subtype, icewalking, Fog cloud, Gust of wind, Freezing fog, Wall of ice, CL 11
Feats: #Feats: 12
Skills: Skill points: 72
Advancement: 33-35 HD (Gargantuan)
Climate/Terrain: Any cold land and underground
Organization: Solitary, pair, or family (1-2 and 2-5 offspring)
Treasure/Possessions: Double Standard

Source: Monster Manual

Breath Weapon (Su): A white dragon has one type of breath weapon, a cone of cold (11d6 cold damage, Reflex save for half damage DC 33). Using a breath weapon is a standard action. Once a dragon breathes, it can't breathe again until 1d4 rounds later. A blast from a breath weapon always starts at the dragon's mouth and extends in a direction of the dragon's choice.

Frightful Presence (Ex): A young adult or older dragon can unsettle foes with its mere presence. The ability takes effect automatically whenever the dragon attacks, charges, or flies overhead. Creatures within a radius of 330 feet are subject to the effect if they have fewer HD than the dragon (33).

A potentially affected creature that succeeds at a Will save (DC 29) remains immune to that dragon's frightful presence for one day. On a failure, creatures with 4 or fewer HD become panicked for 4d6 rounds and those with 5 or more HD become shaken for 4d6 rounds.

Dragons ignore the frightful presence of other dragons.

Cold Subtype

A creature with the cold subtype has immunity to cold. It has vulnerability to fire, which means it takes half again as much (+50%) damage as normal from fire, regardless of whether a saving throw is allowed, or if the save is a success or failure.