Mmm, actually I just looked at the thread again, the Horror definately has SR 90. Take a look
Pseudonatural Ultroloth; CR 30; medium outsider (evil, extraplanar, pseudonatural, yugoloth); HD 18d8+216; hp 360; Init +23; Spd 80ft.; AC 68, touch 33, flatfooted 53; Base Atk +18; Grp +48; Atk +48 melee (2d8+15, tentacle rake); Full Atk: +48/+48/+48/+48/+48/+48 melee (2d8+15, tentacle rake); SA Constant insight, fear aura, improved grab, rotting constriction, spell-like abilities, summon yugoloths, weakness gaze; SQ Alternate form, damage reduction 15/epic and good and silver, darkvision 60 ft., fast healing 4, immunity to acid and poison, resistance to electricity 35, fire 10 and cold 10, spell resistance 90, telepathy 100 ft., true seeing; SV Fort +23 Ref +26 Will +25; AL NE; Str 41 Dex 41 Con 35 Int 28 Wis 38 Cha 28.
The empahsis is mine but its a C&P of the original. Why don't they just give Epic Pseudonaturals Magic Immunity ? at any level above 7, nothing within 7 Challenge Ratings of the creature is going to be able to touch it with SR spells anyway.
Don't forget his 68 AC. That would mean that a 30th level fighter with a modified strength of 38, a +8 weapon of his favored type, along with weapon focus and epic weapon focus would need to roll an unmodified 18 on his first attack roll to hit; everything else would have to be 20s. Seems more than a little too high for a CR 30 encounter to me.