Dragon, Chaos Old (CR 16)

Huge Dragon (Extraplanar)
Alignment: Always chaotic (any)
Initiative: +0; Senses: blindsense 60 ft., darkvision120 ft., low-light vision, and keen senses
Languages: Draconic and either Celestial (chaotic good and some chaotic neutral dragons only) or Abyssal (chaotic evil dragons only)

AC: 34 (-2 size, +26 natural), touch 8, flat-footed 34
Hit Dice: 26d12+182 (351 hp); DR: 15/magic
Fort +22, Ref +15, Will +21
Speed: 60 ft., fly 200 ft. (good), swim 40 ft.
Space: 20 ft./10 ft.
Base Attack +27; Grapple +42
Attack: 1 bite +32, 2 claws +27, 2 wings +27, 1 tail slap +27, 1 crush +27
Damage: 1 bite 2d8+7, 2 claws 2d6+3, 2 wings 1d8, 1 tail slap 2d6, 1 crush 2d8
Special Attacks/Actions: Breath weapon 16d4 (30)
Abilities: Str 25, Dex 10, Con 25, Int 20, Wis 23, Cha 24
Special Qualities: Immunity to compulsion effects, Protection from law, Chaos hammer, entropic shield, Dispel law, mind fog, Word of chaos, SR 30, Fear aura (DC 30)
Feats: #Feats: 9
Skills: Skill points: 136
Advancement: 28-29 HD (Huge)
Climate/Terrain: Any land and underground (Chaos of Limbo)
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: Draconomicon

Breath Weapon (Su): A chaos dragon has two types of breath weapon, a line of energy and a cone of confusion gas. The energy type of its breath weapon is determined randomly each time it uses the breath weapon by rolling d%: 01-20 acid, 21-40 cold, 41-60 electricity, 61-80 fire, 81-100 sonic. Even the dragon itself doesn't know which type of energy it will emit before it actually breathes. Creatures within the cone of confusion gas must succeed on a Will save or be confused for 1d6 rounds plus 1 round per age category of the dragon.

Spell-Like Abilities: 3/day - entropic shield, protection from law, chaos hammer; 1/day - cloak of chaos, dispel law, mind fog, mislead, word of chaos.

Extraplanar Subtype

A subtype applied to any creature when it is on a plane other than its native plane. A creature that travels the planes can gain or lose this subtype as it goes from plane to plane. This book assumes that encounters with creatures take place on the Material Plane, and every creature whose native plane is not the Material Plane has the extraplanar subtype (but would not have when on its home plane). An extraplanar creatures usually has a home plane mentioned in its description. These home planes are taken from the Great Wheel cosmology of the D&D game (see Chapter 5 of the Dungeon Master's Guide). If your campaign uses a different cosmology, you will need to assign different home planes to extraplanar creatures.

Creatures not labeled as extraplanar are natives of the Material Plane, and they gain the extraplanar subtype if they leave the Material Plane. No creature has the extraplanar subtype when it is on a transitive plane; the transitive planes in the D&D cosmology are the Astral Plane, the Ethereal Plane, and the Plane of Shadow.