OK, here is Xi'Parnturil. I don't think he looks as good as he could, though. This concerns especially his Chaos Seed ability.
Oh, and don't take too much offense at the munchkin weapon he uses.
Xi’Parnturil, the Chaosbringer, He who sheds tears and destroys worlds
Xi’Parnturil uses a death slaad advanced to 45 HD as the base creature. He has the Thin (-2 Str, +2 Int) and Blotches of Different Color Variations.
Large Outsider (Chaotic, Evil)
Hit Dice: 45d8+405 (765 hp)
Initiative: +11 (+7 Dex, +4 Improved Initiative)
Speed: 60 ft.
AC: 65 (-1 size, +7 Dex, +39 natural, +5 deflection, +5 insight)
Attacks: 2 claws +57, bite +55; or huge +1 bloodwhip +53/+48/+43/+38
Damage: Claw 3d8+12 and stun, bite 4d6+6; huge +1 bloodwhip 1 plus 1d6 temporary Con plus wounding.
Face/Reach: 5 ft by 5 ft./10 ft. (35 ft. with bloodwhip)
Special Attacks: Stun, spell-like abilities, call slaad, chaotic scream, chaos seed.
Special Qualities: Fast healing 15, damage reduction 40/+7, acid, cold, electricity, fire, sonic resistance 5, telepathy, alternate form, SR 43, turn resistance +4, planar ruler abilities, not limited by height when jumping
Saves: Fort +35, Ref +33, Will +34
Abilities: Str 34, Dex 24, Con 29, Int 28, Wis 26, Cha 26
Skills: Alchemy +35, Balance +35, Climb +61, Escape Artist +56, Hide +52, Intimidate +35, Jump +63, Knowledge (Arcane) +35, Knowledge (the planes) +58, Knowledge (religion) +58, Listen +59, Move Silently +56, Search +58, Spellcraft +35, Spot +59, Tumble +41
Feats: Alertness, Bloodwhip Proficiency, Cleave, Great Cleave, Great Fortitude, Improved Initiative, Iron Will, Lightning Reflexes, Multiattack, Power Attack, Weapon Focus (bite), Weapon Focus (claws), Weapon Focus (bloodwhip)
CR: 33
Alignment: Chaotic evil
Xi’Parnturil might be one of the oldest entities of chaos in existance, although he has long ago been tainted by dark influences. Towering 14 feet high, he has a rather slim body with a skin that, while basically greyish, always flickers in prismatic, but pale colors, and his eyes seem to constantly shed tears that shimmer in several colors. However, whenever such a tear drops to the ground, it vanishes without a trace. Only approximately once per year, such a tear does remain stable and usable to draw a plane closer to Limbo, the swirling chaos that Xi’Parnturil calls home. He carries a dreadful whip with nonmagical capacities beyond any weaponmaker presently alive could ever hope to duplicate. In the legends told about him, he has always carried this Bloodwhip, but he actually only gained and mastered it recently - whatever recently might mean for an undying creature.
Stun (Ex): Xi’Parnturil can use Stunning Fist as the feat, eleven times per day. The save DC is 40.
Spell-like Abilities: At will -
animate objects, circle of death, chaos hammer, cloak of chaos, deeper darkness, detect magic, dimensional anchor, dispel law, fear, finger of death, fireball, fly, identify, invisibility, magic circle against law, power word blind, see invisibility, shatter, word of chaos; 1/day -
fog cloud, implosion, miracle. These abilities are as the spells cast by an 45th level sorcerer (save DC 18 + spell level).
Alternate Form (Su): Xi’Parnturil can shift between his natural and any humanoid form at will as a standard action. He will use any magical item he owns in his humanoid form. Xi’Parnturiel can remain in humanoid form indefinitely. The ability is otherwise similar to alter self cast by a 45th level sorcerer.
Natural Extension (Su): Xi’Parnturil’s bloodwhip is practically an extension of himself. He can use it to penetrate damage reduction up to +7, like he could with his claws and bite.
Call Slaad (Sp): Twice per day, Xi’Parnturil can automatically call up to four red slaadi, three blue slaadi, three green slaadi, three gray slaadi, or two death slaadi, or any other combination of slaadi that adds up to a total of CR 31, as long as no slaad called has a CR higher than CR 23. He can also, with a 80% chance of success, call slaadi up to a total of CR 32.
Chaotic Scream (Su): Breath weapon, 160 ft. long cone of chaotic sound, every 1d4 rounds. Functions as a word of chaos spell. Reflex negates DC 41.
Chaos Seed (Su): Approximately once per year, Xi’Parnturil sheds a tear that is unusually persistent and large, appearing as a sphere of dark, swirling colors. When Xi’Parnturil plants this tear into the earth, it quickly grows into a slaad-like shape from which a chaotic storm spreads. After one hour, this storm covers a 15 mile radius around the shape, which then becomes a true, average death slaad, the Seed Guardian. The storm grows by one mile per week, and for every two miles, the Seed Guardian’s CR is increased by 1, either by additional hit dice, templates, or most unlikely, class levels.
The area of the storm is effectively part of both the original plane and of Limbo, and every day draws it closer to the plane of chaos. Only the death of the Seed Guardian can undo this, and only if it happens withing 1d6 months (roll once for each seed). Any area that was part of the storm longer than that is permanently lost to Limbo. The area that remains behind is a barren wasteland, and a wild magic zone. The original landscape is drawn to Limbo.
Any creature and any attended object in the area must make a Fortitude save (DC 18) or suffer a chaotic change, devised by the DM. The Fortitude save gets harder each time it is made, increasing in it’s DC by +1 for every day that it is made. If it is failed, it resets to 18.
Planar ruler abilities: Increased Speed, Maximum Hit Points, Improved Summoning, Call Slaad, Increase Damage Reduction by 10/+3 (2 abilities), Natural Extension (Bloodwhip), bonus feats (Weapon Focus (Bloodwhip); Iron Will) (2 abilities), Chaos Seed (24 abilities), Extra Spell-like abilities, Improved Fast Healing +10 (2 abilities), Not limited by height during jump, Enlarge Cone*3, Improved Natural Armor +20 (5 abilities)
Possessions: Xi’Parnturil’s Bloodwhip(a huge +1 bloodwhip).
Bloodwhip: A bloodwhip is an ancient, powerful ranged weapon that resembles a normal whip with several wicked barbs. Despite it’s powers, it is not magical, but crafted with an expertise not repeated in eons.
Normally, bloodwhips are Medium-Size and deal 1d4 points of temporary Con damage on a successful hit as well as functioning as a wounding weapon, by ripping large wounds into the opponents’ flesh. Both effects are doubled on a critical hit. Xi’Parnturil’s Bloodwhip is special in being Large (dealing 1d6 points of temporary Con damage) and enchanted with a +1 enhancement. This enhancement adds to the to-hit chance and the normal damage, which is 0 for a bloodwhip, so Xi’Parnturil’s Bloodwhip deals 1 point of normal damage in addition to the Con damage and the wounding.
If characters not proficient with a bloodwhip try to use one, they are in for a shock: instead of the normal -4 penalty, they suffer a -30 penalty, and they are in danger of hurting themselves. Whenever a non-proficient character rolls a 1 on his attack roll, he must make a second attack roll. If he would miss his target on the second roll, he has hit himself with the bloodwhip, dealing the usual damage to himself.
Note that bloodwhips, like normal whips, are ranged weapons, although the bloodwhip has a range increment and maximum of 30 ft. The character can use the bloodwhip like a normal whip to trip and disarm his foe. Note that armor only grants it normal protection against a bloodwhip. That means that, unlike a whip, it can penetrate armor and natural armor values above +1 and +3, respectively.
Proficiency with a bloodwhip is not gained easily. It requires a base attack bonus of +25 along with four exotic weapon proficiencies, or, if the character does not have enough exotic proficiencies, he can increase the BAB requirement by +4 for every exotic proficiency not possessed (Xi’Parnturil used this option, gaining the bloodwhip proficiency as the last regular feat of his advancement. His Focus in the bloodwhip is a bonus feat that he gained as a planar ruler.).
A bloodwhip has an estimated market price of 250,000 gp, but it cannot be bought in any shop. Bloodwhips are either granted by beings that know of these weapons, or found in long lost cities of forgotten civilizations. The market price is only given for purposes of determining the fair treasure share and for crafting the weapon. Crafting a bloodwhip requires Craft checks with a DC of 90, but for the progress of the crafting, the DC is considered to be 15. Thus, for a Weaponsmith who constantly rolls a 90 on his Craft check, it takes about 35,5 years to complete a single bloodwhip, as opposed to nearly 6 years it would take under normal rules.