Dragon, Obsidian Very Old (CR 20)
Huge Dragon (Fire)
Alignment: Always neutral evil
Initiative: +0; Senses: blindsense 60 ft., darkvision120 ft., low-light vision, and keen senses
AC: 38 (-2 size, +30 natural), touch 8, flat-footed 38
Hit Dice: 31d12+186 (387 hp); DR: 15/magic
Fort +23, Ref +17, Will +20
Speed: 40 ft., fly 150 ft. (poor), burrow 20 ft., swim 20 ft.
Space: 15 ft./10 ft. (15 ft. with bite)
Base Attack +31; Grapple +50
Attack: 1 bite +40, 2 claws +35, 2 wings +35, 1 tail slap +35, 1 crush +35
Damage: 1 bite 2d8+11, 2 claws 2d6+5, 2 wings 1d8, 1 tail slap 2d6, 1 crush 2d8
Special Attacks/Actions: Breath weapon 18d10 (31)
Abilities: Str 33, Dex 10, Con 23, Int 31, Wis 17, Cha 16
Special Qualities: Fire subtype, planar travel, Firefall, Biofeedback, burning ray, Whitefire, wall of ectoplasm, Ectoplasmic armor, flaming shroud, SR 30, Fear aura (DC 28), Manifester level 13
Feats: #Feats: 11
Skills: Skill points: 316
Advancement: 32-33 HD (Huge)
Climate/Terrain: Inner Planes, warm mountains, 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: Double standard
Fire Subtype (Ex): An obsidian dragon is immune to fire but takes double damage from cold, except on a successful save.
Breath Weapon (Su): An obsidian dragon has one breath weapon: a cone of fire.
Planar Travel (Su): Obsidian dragons have the innate ability to pass instantly between the Material Plane and the Inner Planes, where they often make their homes.
Psionics (Sp): 3/day -- biofeedback, burning ray, ectoplasmic armor, firefall, flaming shroud, plane shift, wall of ectoplasm, whitefire; 1/day -- genesis, mind store. Manifester level varies by age; save DC d20 + appropriate ability modifier + power level.
Attack/Defense Modes: mind thrust/thought shield. An obsidian dragon manifests powers and gains additional attack and defense modes as if it were a psion with Metacreativity as its primary discipline.
Skills: An obsidian dragon has the Appraise skill for free at 1 rank per Hit Die.
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.