Dragon, Arboreal Ancient (CR 20)

Gargantuan Dragon (Extraplanar)
Alignment: Always chaotic good
Initiative: +0; Senses: blindsense 60 ft., darkvision120 ft., low-light vision, and keen senses
Languages: Celestial, Draconic, Elven, Sylvan

AC: 39 (-4 size, +33 natural), touch 6, flat-footed 39
Hit Dice: 32d12+288 (496 hp); DR: 20/magic and 5/lawful
Fort +27, Ref +18, Will +25
Speed: 60 ft., fly 200 ft. (clumsy)
Space: 40 ft./15 ft.
Base Attack +32; Grapple +57
Attack: 1 bite +41, 2 claws +36, 2 wings +36, 1 tail slap +36, 1 crush +36, 1 tail sweep +36
Damage: 1 bite 4d6+14, 2 claws 2d8+7, 2 wings 2d6, 1 tail slap 2d8, 1 crush 4d6, 1 tail sweep 2d6
Special Attacks/Actions: Breath weapon 20d8 (35)
Abilities: Str 39, Dex 10, Con 28, Int 22, Wis 25, Cha 25
Special Qualities: Immunity to acid, sonic and enchantment magic, Alternate form, Telekinesis, Baleful Polymorph, Ottos Irresistable Dance, SR 27, Fear aura (DC 33)
Feats: #Feats: 11
Skills: Skill points: 198
Advancement: 33-34 HD (Gargantuan)
Climate/Terrain: Any land and underground (Olympian Planes of Arborea)
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 #321

Breath Weapon (Su): An arboreal dragon has one breath weapon, a cone of razor-sharp thorns that deal piercing damage. A creature within the cone may make a Reflex save to take half damage.

Alternate Form (Su): A young or older arboreal dragon can assume any animal, fey, or humanoid form of Medium size or smaller as a standard action three times per day. This ability functions as a polymorph spell cast on it by a 10th-level caster, except that the dragon does not regain hit points for changing form and can only assume the form of an animal, fey, or humanoid. The dragon can remain in its animal, fey, or humanoid form until it chooses to assume a new one or its natural form.

Spell-like Abilities: 3/day - telekinesis; baleful polymorph; 1/day - Otto's irresistible dance.

Skills: Climb, Spellcraft, and Survival are considered class skills for arboreal dragons.

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.