Dragon, Radiant Ancient (CR 21)

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

AC: 49 (+32 natural, +10 deflection, +1 Dex), touch 17, flat-footed 48
Hit Dice: 36d12+324 (558 hp); DR: 20/magic and 5/evil
Fort +29, Ref +20, Will +29
Speed: 60 ft., fly 150 ft. (poor)
Space: 40 ft./15 ft.
Base Attack +36; Grapple +64
Attack: 1 bite +48, 2 claws +43, 2 wings +43, 1 tail slap +43, 1 crush +43, 1 tail sweep +43
Damage: 1 bite 4d6+16, 2 claws 2d8+8, 2 wings 2d6, 1 tail slap 2d8, 1 crush 4d6, 1 tail sweep 2d6
Special Attacks/Actions: Breath weapon 20d10 (37)
Abilities: Str 43, Dex 10, Con 29, Int 26, Wis 29, Cha 28
Special Qualities: Immunity to light effects, daylight, dispel darkness, searing light, healing touch, sunburst, SR 37
Feats: #Feats: 13
Skills: Skill points: 294
Advancement: 37-38 HD (Gargantuan)
Climate/Terrain: Any land and underground (Celestia)
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

Young and older radiant dragons' natural weapons are treated as magic weapons for the purpose of overcoming damage reduction.

Breath Weapon (Su): A radiant dragon has two types of breath weapons, a line of force or a cone of light. Creatures caught within the cone must make Fortitude saves or be blinded for 1d6 rounds plus 1 round per age category of the dragon. A successful save means the creature is merely dazzled for the same duration. Sightless creatures are immune to the cone of light breath weapon.

Dispel Darkness (Su): A juvenile or older radiant dragon automatically dispels any darkness spell (whose level is equal to or less than his age category) within 60 feet.

Healing Touch (Su): An old or older radiant dragon can generate any one of the following effects with its touch: cure critical wounds, regenerate, remove blindness/deafness, remove disease, remove paralysis, or restoration. It may use its healing touch a number of times per day equal to its age category.

Spell-Like Abilities: At will - daylight; 3/day - searing light; 1/day - prismatic sphere, sunburst.

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.