Dragon, Iron Ancient (CR 23)

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

AC: 22 (-4 size, +16 natural) touch 6, flat-footed 22
Hit Dice: 34d12+306 (527 hp); DR: 15/magic
Fort +28, Ref +19, Will +27
Speed: 40 ft., burrow 40 ft., fly 200 ft. (clumsy)
Space: 40 ft./15 ft.
Base Attack +34; Grapple +61
Attack: 1 bite +45, 2 claws +40, 2 wings +40, 1 tail slap +40, 1 crush +40, 1 tail sweep +40
Damage: 1 bite 4d6+15, 2 claws 2d8+7, 2 wings 2d6, 1 tail slap 2d8, 1 crush 4d6, 1 tail sweep 2d6
Special Attacks/Actions: Breath weapon 20d10 (36)
Abilities: Str 41, Dex 10, Con 29, Int 26, Wis 27, Cha 26
Special Qualities: Alternate form, immunity to fire, vulnerability to cold, Heat metal, Stone shape, Detect thoughts, Wall of iron, Transmute rock to mud, CL 15th, SR 28, Fear aura (DC 35)
Feats: #Feats: 9
Class Skills: Disguise, Gather Information, Skill points: 278, and and Jump
Advancement: 35-36 HD
Climate/Terrain: Temperate hills and mountains
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

Source: Dragon #356

Alternate Form (Su): An iron dragon can assume any animal or humanoid form of Medium size or smaller as a standard action three times per day. The dragon can remain in its animal or humanoid form until it chooses to assume a new one or return to its natural form.

Metalsense (Ex): all ferrous dragons can sense the location and amount of any non-precious metal (precious metals include adamantine, copper, gold, mithral, platinum, and silver) within a distance of 30 feet x the dragon's age category. This makes it nearly impossible to sneak on a ferrous dragon when wearing armor or wielding weapons made of iron or other nonprecious metals. Like blindsense, opponents the dragon can't actually see still have total concealment against the dragon.

Breath Weapon (Su): An iron dragon has two types of breath weapon, a cone of superheated sparks (dealing half electricity and half fire damage), and a cone of sleep gas. Creatures within a cone of sleep gas must succeed on a Will save or fall asleep, regardless of HD, for 1d6 rounds plus 1 round per age category of the dragon.

Spell-like Abilities: 3/day - heat metal, detect thoughts, transmute rock to mud, wall of iron.

Skills: Disguise, Gather Information, and Jump are considered class skills for iron dragons.

Fire Subtype

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