Dragon, Song Great Wyrm (CR 25)

Gargantuan Dragon (Electricity)
Alignment: Always either chaotic good or chaotic neutral
Initiative: +0; Senses: blindsense 60 ft., darkvision120 ft., low-light vision, and keen senses
Languages: Tongues SA

AC: 43 (-4 size, +37 natural), touch 6, flat-footed 43
Hit Dice: 38d12+304 (513 hp); DR: 20/magic
Fort +28, Ref +21, Will +29
Speed: 40 ft., fly 150 ft. (clumsy)
Space: 20 ft./15 ft. (20 ft. with bite)
Base Attack +38; Grapple +62
Attack: 1 Bite +46, 2 claws +41, 2 wings +41, 1 Tail Slap +41, 1 crush +41, 1 Tail sweep +41 melee; Breath +46 ranged
Damage: 1 bite 4d6+12, 2 claws 2d8+6, 2 wings 2d6+6, 1 tail slap 2d8+18, 1 crush 4d6+18, 1 tail sweep 2d6+18; Breath Weapon 24d6 (36)
Special Attacks/Actions: Breath Weapon 24d6 (36); fear (DC 38), SR 34
Abilities: Str 35, Dex 10, Con 27, Int 32, Wis 32, Cha 33
Special Qualities: Change shape, true seeing, tongues, light, darkness, feather fall, blink, teleport, heal, polymorph any object, electricity and poison immunity, plane shift
Feats: #Feats: 13
Class Skills: Bluff, Disguise, Perform, and Skill points: 424
Advancement: 39+ HD (Gargantuan)
Climate/Terrain: Any land
Organization: Solitary, pair, or family (1-2 and 2-5 offspring)
Treasure/Possessions: Double Standard

Source: Monster Compendium: Monsters of Faerûn

Breath Weapon (Su): A song dragon has one breath weapon, a cone of electrically charged gas. Using a breath weapon is a standard action. Once a dragon breathes, it can't breathe again until 1d4 rounds later. A blast from a breath weapon always starts at the dragon's mouth and extends in a direction of the dragon's choice.

Alternate Form (Su): Song dragons can freely use an ability much like polymorph self to assume human form. They always appear as human females, and each song dragon has a unique human form that it assumes each time it changes shape. The song dragon's Strength, Dexterity, and Constitution scores become human average (Str 10, Dex 11, Con 10), but its hit points are unaffected by this change. A song dragon can employ its spells and special abilities - except its breath weapon - in either form.

Changing from dragon to human form requires 2 rounds; reversing the change takes only 1 round. During this time, the song dragon cannot move and can only use its spells or breath weapon; other actions and attacks are impossible. The change rends all known bonds, clothing, and other confinements, without harm to the song dragon.

True Seeing (Su): Song dragons have true seeing (as the spell) to a range of 15 feet. This ability is always active.

Tongues (Su): Song dragons can communicate in any language through the use of an innate tongues ability that is always active.