Dragon, Tarterian Ancient (CR 20)

Gargantuan Dragon (Extraplanar)
Alignment: Always neutral evil or chaotic evil
Initiative: +0; Senses: blindsense 300 ft., darkvision 1000 ft., and low-light vision
Languages: Draconic

AC: 37 (-4 size, +31 natural), touch 6, flat-footed 37
Hit Dice: 32d12+256 (464 hp); DR: 20/magic and 5/good
Fort +26, Ref +18, Will +24
Speed: 60 ft., fly 200 ft. (clumsy)
Space: 20 ft./15 ft. (20 ft. with bite)
Base Attack +32; Grapple +59
Attack: 1 bite +43, 2 claws +38, 2 wings +38, 1 tail slap +38, 1 crush +38, 1 tail sweep +38
Damage: 1 bite 4d6+15, 2 claws 2d8+7, 2 wings 2d6, 1 tail slap 2d8, 1 crush 4d6, 1 tail sweep 2d6
Special Attacks/Actions: Breath weapon 18d8 (34)
Abilities: Str 41, Dex 10, Con 27, Int 22, Wis 23, Cha 22
Special Qualities: Force resistance, strength of will, freedom of movement, Otilukes resilient sphere, Maze, SR 30, Fear aura (DC 32)
Feats: #Feats: 11
Skills: Skill points: 198
Advancement: 33-34 HD (Gargantuan)
Climate/Terrain: Any land and underground (Carceri)
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

Breath Weapon (Su): A Tarterian dragon has two types of breath weapon, a line of disruptive force or a cone of will-sapping gas. Creatures within the cone must succeed on a Will save or be affected by a crushing despair effect, taking a -2 penalty on saving throws, attack rolls, ability checks, skill checks, and weapon damage rolls for 1 round per age category of the dragon.

Force Resistance (Ex): Tarterian dragons have a +4 racial bonus on saving throws against force-based spells and effects.

Freedom of Movement (Su): Tarterian dragons can move and attack normally despite any magic that usually impedes movement, such as hold monster, paralysis effects solid fog, slow, and web spells.

Strength of Will (Ex): Tarterian dragons have a +4 morale bonus on saving throws against charm and compulsion effects.

Spell-Like Abilities: 1/day - forcecage, imprisonment, maze, Otiluke's resilient sphere.

Frightful Presence (Ex): An ancient dragon can unsettle foes with its mere presence. The ability takes effect automatically whenever the dragon attacks, charges, or flies overhead. Creatures within a radius of 300 feet are subject to the effect if they have fewer HD than the dragon (35).

A potentially affected creature that succeeds at a Will save (DC 34) 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 5 or more HD become shaken for 4d6 rounds.

Dragons ignore the frightful presence of other dragons.

Immunities (Ex): All dragons are immune to sleep and paralysis effects.

Spell Resistance (Ex): As dragons age, they become more resistant to spells and spell-like abilities.

Blindsight (Ex): A dragon can ascertain creatures by non-visual means (mostly hearing and scent, but also by noticing vibration and other environmental clues) with a range of 300 feet.

Keen Senses (Ex): A dragon sees four times as well a human in low-light conditions and twice as well in normal light. It also has darkvision with a range of 1000 feet and scent ability to 300 feet.

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.