This creature is an Adult Brass Dragon (from the SRD) with a Mithral Metal-Clad emplate applied from Green Ronin's Advanced Bestiary.

It was originally created just to test out the template, but could be used as some sort of unique servant of Good, or a member of an entire species of Mithral Dragons.

Large Dragon (Fire)
Hit Dice: 19d12+105 (218 hp)
Initiative: +0
Speed: 60 ft, fly 200 ft (poor), burrow 30 ft
AC: 35 (-1 size, +26 natural)
Attacks: Bite +26 melee, 2 claws +21 melee, 2 wings +21 melee, tail slap +21 melee
Damage: Bite 2d6+8, claw 1d8+5, wing 1d6+5, tail slap 1d8+11
Face/Reach: 5 ft by 10 ft / 5 ft
Special Attacks: Breath weapon, spell-like abilities, frightful presence
Special Qualities: Fire subtype, immunities, DR 5/Magic, blindsight, keen senses, Medium fortification, vulnerability to electricity, SR 20
Saves: Fort +16, Ref +11, Will +13
Abilities: Str 27, Dex 10, Con 21, Int 14, Wis 15, Cha 16
Skills: Bluff +22, Concentration +24, Diplomacy +22, Escape Artist +19, Listen +21, Search +21, Sense Motive +21, Spellcraft +21, Spot +21, Swim +4
Feats: Hover, Flyby Attack, Power Attack, Cleave, Snatch

Challenge Rating: 16
Alignment: Always chaotic good

SA–Breath Weapon (Su): Line of fire, 80 feet long, every 1d4 rounds; damage 6d6, Reflex half DC 23. This dragon can use a cone of sleep instead, forcing subjects who fail a Will save to fall asleep for 1d6+6 rounds.

SA–Frightful Presence (Ex): Dragons can unsettle foes with their mere presence. This ability takes effect automatically (radius 180 ft) whenever the dragon attacks, charges, or flies overhead. A potentially affected creature (one with less than 19 HD) that succeeds at a Will save (DC 22) remains immune to that dragon's frightful presence for one day. On a failure, creatures with 4 or fewer HD become panicked for 4d6 rounds and those with more than 5 HD become shaken for 4d6 rounds. Dragons ignore the frightful presence of other dragons.

SA–Spell-Like Abilities: At will - speak with animals; 3/day - endure elements (radius 60 ft); 1/day - suggestion.

SQ–Immunities (Ex): Immune to sleep, paralysis.

SQ–Blindsight (Ex): Dragons can ascertain creatures by nonvisual means (mostly hearing and scent, but also by noticing vibrations and other environmental clues); this dragon's range is 180 feet.

SQ–Keen Senses (Ex): Dragons can see four times as well as humans in low-light conditions and twice as well in normal light. They also have darkvision (range 600 feet).

SQ–Medium Fortification (Ex): Whenever a sneak attack or critical hit is scored against a mithral dragon, there is a 75% chance the extra damage is negated and damage is rolled normally.

SQ–Vulnerability to Electricity (Ex): A Mithral Dragon takes half as much damage again as normal from electricity, regardless of if a saving throw is allowed and regardless if the save is a success or a failure.

SQ–Fire Subtype (Ex): Fire immunity, double damage from cold except on a successful save.

Spells Known (cast 6/7/7/4; as a level 7 sorcerer):
0–detect magic, resistance, detect poison, read magic, dancing lights, ghost sound, mage hand;
1–endure elements, mage armor, divine favor, cure light wounds, shield;
2–bull's strength, cat's grace, blur;
3–haste, dispel magic.