Here is a version of the Chaos Orb from Necromancer's Game's Tome of Horror books, that I loved the second I saw it. Perfectly fit what I thought a typical chaos acting creature should be. Hope you drive your players a little further towards madness.
Chaonaos (Chaos Drift or Chaos Orb)
NE Large Sized Aberration
Init variable; Senses darkvision 60 ft.,low-light vision, Perception +15
DEFENSE
AC 19, touch 12, flat-footed 16 (+7 Natural, +3 Dexterity)
hp 45 (10d8);
Fort +5, Ref +6, Will +7
Morale 19 (Fearless)
OFFENSE
Speed 5 ft., Fly 40 ft
Melee +10 Bite (1d8+4), Pseudopod +13 (Varies)
SA Chaos strike
STATISTICS
Str 18, Dex 16, Con 10, Int 15, Wis 10, Cha 13
Base Atk +8; CMB +12; CMD 25
Feats: Attack Focus (Pseudo-Pod), Skill Focus (Perception), Great Fortitude, Fly-By Attack, Spell Focus (Chaos Strike),
Skills Perception +15, Knowledge (Arcane) +15, Knowledge (Chaos) +15,Knowledge (Religion)+15, Fly +24
SQ Spell Engine, Immune to mind spells, Resist 20 (all) elemental types, Damage Reduction 15/law
ECOLOGY
Environment mountains & underground
Organization solitary
Treasure Double standard
Advancement: Huge (11-18 HD)
At first glance, this creature appears as a ten foot large radius dull-gray skinned orb, without any visible organs of any kind. Its skin is constantly shifting, and flashes of colour and energy likewise skirt across its surface, at random intervals small obtrusions appear (pseudo-pods, eyes, tails, etc). They have a capacity for capturing and throwing magical energy back at their opponents, using a chaos strike ability, but since they do not like to work with others or follow orders, little is known about their powers.
Little is known about the origins of a chaos drift but it is believed to originate on the outer planes, most likely in a chaotic domain. These beings usually end up on prime worlds either by being summoned or slipping through open portals. Their superb battlefield calculations indicate sentience but what if any goals it has on the prime worlds is little understood. Unlike lawful creatures, they do not serve Masters except when initially summoned, and never serve other agents of chaos.
They usually reside in remote locations, living solitary lives dedicated to a pursuits, usually one of an artistic or knowledge. They survive by using their pseudo-pods to kill small animals. Most care little about interaction with other creatures, especially other chaotic beings. When creatures invade "their space", they do their best to destroy them. They reproduce by splitting into four smaller versions of themselves when expiring naturally, these lessers act as a family uint for approximately three years until fully grown and separate from each other.
Combat
Every round is slightly different for a chaos drift, as it has differing possibilities that emerge, increasing its physical pseudopod attachs and increasing their chaos strike possibilities. It only needs to roll initiative every six rounds, on the first round it acts incredibly quick and then slows down.
It physically attacks via a pseudo-pod that emerges from its body – each round it inflicts different amount of damage. In addition, every round a spell is cast, a chaos strike is created, rolling on the table below for the effect. It can attack one creature in any cardinal direction (North, South, East, West, Above or Below).
Attack Mods: will not effect chaos strikes created by other spell casters (Roll)
1st round: +12 initiative, Slam 1d8, 100% chaos strike (roll d4 on chaos strike subtable)
2nd round: +8 initiative to original roll, Slam 1d12, 50% chaos strike (roll d6 on subtable)
3rd round: +4 initiative to original roll, Slam 2d10, 20% chaos strike (roll d8 on subtable)
4th round: +0 initiative to original roll, Slam 2d8, 100% chaos strike, 50% 2nd chaos strike (roll d10 on subtable)
5th round: -4 initiative to original roll, Slam 2d4, 100% chaos strike, 50% 2nd chaos strike, 50% 3rd chaos strike (roll d12 on subtable)
6th round: -8 initiative to original roll, Slam 5d10, 0% chaos strike (roll d12 on subtable)
Roll for each strike each time directed towards either the offending spellcaster or the largest deemed threat if generated by the orb itself. All spells are cast as a 12th level
1 Energy Rebound: spell energy returned to spell-caster, does not lose memorized spell; if fail concentration check cannot cast the spell anyway
2 Confusion (DC 16), lasts 1d10 hours
3 3d10 blast as fireball, any elemental damage, (DC 16 to avoid)
4 Paralyzed (DC 16), lasts 1d8 minutes
5 1d6 attribute drain (roll 1d6 to determine) DC 15 to avoid, lasts 1d10 hours
6 Lesser Confusion (DC 14), lasts 1d12 minutes
7 1d4 negative levels (DC 16) lasts 1d12 hours
8. Blind (DC 14) lasts 1d4 minutes
9. 3d10 sonic (include worn items)
10 5d10, any damage, DC 18
11 Petrifaction (DC 13) Permanent
12 Feeblemind (DC 18) lasts 1d12 hours
Note: This is a version of Chaos Orb which comes from one of the Necromancer Games Tome of Horror books, no copyright infringement intended, it's just a really cool idea for a creature that I love using in my dungeon games.