Immunities
When you design monsters especially with UK's system in mind, DON'T give anything an immunity to anything. Because immunities are dangerous, and lead to things like this....
Void Cat:
HP: 27( 1d8+12+7,Max HP)
Speed 90 ft
AC: 51(+2size+10 dex+12 insight+12 luck +5 natural AC)
BAB +0,-1
Attack: Claw +37 melee (1d3+23+disintigrating touch)
Full Attack: 2 Claws +37 melee (1d3+23+disintegrating touch) Bite +28 (1d4+23+disintegrating touch)
Special Attacks: Disintegrating touch, Vortex
Special Qualities: Low-light Vision, Scent, Immunities,Spell-Like Abilities, Planar Travel, Fast Healing 20, DR 15/epic, SR:15+CR, Regeneration 1
Saves: +19/+22/+18
Attributes: 18/30/25/17/29/22
Feats: Weapon Finesse, Evasion, Improved Evasion, Mettle of Fortitute, Mettle of Will, Improved Mettle of Fortitude, Improved Mettle of Will, Dire Charge
Skills: +10 competence bonus, +4 on climb, Hide and Move Silently, +8 on jump and balance, with dex mod instead of str for climb and jump checks
* In areas of tal grass or heavy undergrowth the hide bonus rises to +8
It has 20 skill points, assign as you wish, treat all skills as class skills.
CR: 76
Disintegrating Touch and Vortex: See ELH under Umbral Dot
Save DC is 33 for Disintegrating Touch and 33 and 17 for vortex
Spell-Like Abilities(Sp):
Haste,Greater Dispelling, See Invisibility 3/day,
Planar Travel (Ex):
Teleport without Error, planeshift,dimension dorr, or Ethereal jaunt at will as a standard action.
Immunities(Ex): Immune to Cold, Fire, Acid, Sonic, Lightning, Chronal Damage, Radiation, Aging, Positive Energy, Negative Energy, Alignment Damage, Bane Damage, Force effects, Light effects and blindness, Ability Score Loss, Critical Hits, Disease, Energy Drain, Magic, Mind Affecting Effects, Disintegration, Petrification, Poison, Polymorphing, Psionics, Death Effects, Sleep/Paralysis/Stunning, Spells, and Takes no damage from weapons.
Regeneration (Ex): The void cat takes damage ONLY from Divine, Profane, and Arcane Damage, even these 3 types only do subdual damage. The void cat can only be destroyed by bringing it to -20 HP and feeding it to itself while it is unconsious.
It is the void, all of the empty space that used to be where the multiverse currently resisdes , in the shape of a housecat. It looks like a representation of a cat was just cut from the universe when ever it is seen.