Dragon, Chromium, Great Wyrm (CR 25)
AC: 41 (-4 size, +35 natural), touch 6, flat-footed 41
Hit Dice: 37d12+259 (499 hp); DR: 20/magic
Fort +29, Ref +21, Will +28
Speed: 40 ft., fly 200 ft. (clumsy), swim 60 ft.
Space: 40 ft./15 ft.
Base Attack +39; Grapple +66
Attack: 1 bite +50, 2 claws +45, 2 wings +45, 1 tail slap +45, 1 crush +45, 1 tail sweep +45
Damage: 1 bite 2d8+15, 2 claws 2d6+7, 2 wings 1d8, 1 tail slap 2d6, 1 crush 2d8, 1 tail sweep -
Special Attacks/Actions: Breath weapon 21d8 (37)
Abilities: Str 41, Dex 10, Con 27, Int 24, Wis 25, Cha 24
Special Qualities: Immunity to cold, vulnerability to fire, Pass without trace, Ice shape, Wall of ice, Gelid blood, Flesh to crystal, CL 19th, SR 31, Fear aura (DC 36)
Feats: #Feats: 13
Class Skills: Appraise, Bluff, Skill points: 279, and and Jump
Advancement: 38+ HD (Gargantuan)
Climate/Terrain: Any cold mountain or underground
Organization: Solitary (1 dragon, any age), clutch (1d4+1 wyrmlings, very young, young, juvenile, or young adults), family (pair of mature adults and 1d4+1 offspring)
Treasure/Possessions: Triple Standard
Breath Weapon (Su): A chromium dragon has two types of breath weapon, a line of solid ice (cold) and a cone of freezing crystals. Creatures within a cone of freezing crystals take 1 point of Dexterity damage per age category of the dragon (Fortitude half).
Flesh to Crystal (Sp): A great wyrm chromium dragon can use this ability once per day. It is similar to a flesh to stone spell, except that the victim is turned into a crystalline statue rather than stone (DC 17 + the dragon's Cha modifier). As a crystalline object, it is especially vulnerable to effects that damage crystal, such as a shatter spell. This is the equivalent of a 7th-level spell.
Spell-Like Abilities: 3/day - pass without trace (ice and snow only); 2/day - ice shape (as stone shape, but applies to ice instead of stone), wall of ice; 1/day - gelid blood*. (*If you are not using Frostburn in your campaign, replace this spell with eyebite.)
Skills: Appraise, Bluff, and Jump are considered class skills for chromium dragons.
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.