Hoary Steed (CR 9)

Large Magical Beast (Cold)
Alignment: Always neutral evil
Initiative: +8 (+4 Dex, +4 Improved Initiative); Senses: Listen +8 and Spot +13

AC: 23 (-1 size, +4 Dex, +10 natural) touch 13, flat-footed 19
Hit Dice: 12d10+36 (102 hp); DR: 5/magic and cold iron
Fort +11, Ref +12, Will +5
Speed: 40 ft., fly 90 ft. (good)
Space: 10 ft./5 ft.
Base Attack +12; Grapple +22
Attack: Hoof +17 melee
Full Attack: 2 hooves +17 melee, bite +15 melee
Damage: Hoof 3d6+6, bite 5d8+3
Special Attacks/Actions:
Abilities: Str 22, Dex 18, Con 17, Int 6, Wis 13, Cha 14
Special Qualities: Cold immunity, fire vulnerability, air walk, astral projection and etherealness, magic circle against good, misty breath, SR 20, immunities
Feats: Alertness, Endurance, Flyby Attack, Improved Initiative, Multiattack
Skills: Jump +10, Listen +8, and Spot +13
Advancement: 13-24 HD (Large); 25-36 HD (Huge)
Climate/Terrain: Any cold
Organization: Solitary (with rider)
Treasure/Possessions: None

Source: Epic Level Handbook

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.