In PF, how would you optimize for soloing Rappan Athuk?

[Kaouse]

Neither warlord (or pally) Cha to saves or maneuvers are needed to achieve 29+ to your saves. And as is usually the case, also in the final fight against Orcus you actually only need to worry about a high Fort and Will, not Ref, and only to (Su), (Sp) and spells, most notably vs fear (Will DC 41 aura) and death (Fort DC 40 on melee hit with Orcus' wand). Here are some example numbers from two initiator builds I've previously posted on GitP, both admittedly intended as defenders, but optimized mainly for melee control and active defense (not for high passive defense numbers specifically):

Nelly Nephilim Monk 1, Warlord 1, Wilder 1, Warder 1, Zealot 6, Awakened Blade 10:
AC 52, touch 22, flat-footed 39; +5 dodge vs traps (14 armor, 8 natural, 8 shield, 2 Dex, 5 deflection, 6 insight, 5 dodge, -4 size, -2 rage)
Fort +34 (8 Con, 3 awakened blade, 2 monk, 2 warder, 2 warlord, 5 zealot, 5 resistance (pauldrons), 1 competence (pale green prism), 6 insight (Stance of the Inner Eye))
Will +35 (5 Wis, 5 awakened blade, 2 monk, 2 warder, 2 wilder, 5 zealot, 5 resistance (pauldrons), 1 competence (pale green prism), 6 insight (Stance of the Inner Eye), 2 morale (rage))
+5 profane to AC and saves vs attacks and effects caused by shaken, frightened, panicked or cowering enemy (Black Seraph Style)
Combat Reflexes, uncanny dodge & improved uncanny dodge, 55' melee reach, dirty trick CMB +75 (also as AoO), Improved Trip CMB +92

Eddie Pincerhand (progressed to 20th) Monk 4, Warder 10, Barbarian 2, Formless Master 4
AC 50, touch 28, flat-footed 41 (15 armor, 10 natural, 7 shield, 4 Dex, 5 deflection, 5 dodge, -4 size, -2 rage)
Fort +30 (8 Con, 3 barbarian, 4 monk, 7 warder, 2 formless master, 5 resistance (piercings), 1 competence (pale green prism))
Will +29 (7 Wis, 4 monk, 7 warder, 2 formless master, 2 resistance (piercings), 1 competence (pale green prism), 4 insight (crystal mask of mindarmor), 2 rage)
+5 profane to AC and saves vs attacks and effects caused by shaken, frightened, panicked or cowering enemy (Black Seraph Style)
+5 to saves vs mind-affecting (Abomination Shift)
+4 to saves vs fear (rallying armor)
50% chance to avoid SA or crit damage and effects (Sensory Shift)
SR 20, ignores first 12 death effects (Scarab of Protection)
Combat Reflexes & uncanny dodge, 55' melee reach, grab CMB +84 (maintain as AoO), Greater Trip CMB +93

Note that it's unlikely Orcus can activate his aura of fear before he's at the very least shaken if fighting either of the above example builds (meaning they both will likely make the save on a roll of 2+). Both these builds also have access to maneuvers to increase the above numbers considerably, such as Lord of the Pridelands (Golden Lion 9th) for up +10 morale to attack, damage, AC and saves for one round, and both may initiate that maneuver each round and still typically have a lot more actions left than Orcus has per default. IOW, I'd sure put my money on Orcus and his cronies being the only ones peeing their proverbial pants in fear in a fight against either of these two. (For a more detailed example opening round in a high CR encounter, check out Nelly above against the CR 30 demon lord Pazuzu and three CR 25 balor lords here.)

Sure, but at that point the whole tromp l'oeille idea has become highly dependent on GM fiat rather than hard RAW, and therefore it has most likely also been reduced to not much more than a weapon to use on the final levels rather than a strategy to solo the entire adventure. And at least AFAICT from skimming through the adventure, those final levels are probably going to be the easiest for an optimized PC (or party) regardless of any aid from a construct copy of Orcus.

This is cool. I also made a build optimized for defense and control a while back. It's a straight level 20 Mageknight with the Martial Mageknight and Doomblade archetypes:

Quin T. Ence
His AC is 43, but thanks to Active Defense and Combat reflexes, it's mostly an even 50. Thanks to Quickened Reflexes, he can spike that up further to an AC of 60, though Quickened Reflexes costs spell points to use. Thanks to Unarmored Training and Deflecting Shield, all of his AC also applies against Touch. He also has Uncanny Dodge, to prevent himself from being flat-footed.

His saves are all +33, and he has both Stalwart and Evasion, as well as a few Protection Sphere Aegis abilities to mitigate some of the more well known "no save, just suck" abilities in the game (emotion effects, alignment effects, & death effects, all of which increase his morale bonus on saves against those things by a further +3 to 36 and forcibly always grant him a save). The Safety rally even lets him reroll a failed save once per round.

Where he really shines is physical damage mitigation though. Thanks to the unbreakable Mystic Combat, he can temporarily gain DR 20/-, on top of resilient momentum that allows him to reduce the damage of an attack by 7 (casting mod) without an action, temp hp that can be refreshed each round as a free action, and a delayed damage pool that turns into nonlethal damage when emptied. Against massive spike damage, he can even use Disperse Force to negate a single threat per round.

Offensively, he relies on abusing Ghostly Admixture to inflict negative levels with each of his attacks. With Thanatopic Spell, even undead and people warded by Death Ward aren't safe. He also has Time Thief's Admixture, forcing opponents to make saves with each attack, or become dazed via Steal Time, which also gives him another standard action attack. Thanks to Greater Admixture, he can combine the two. And thanks to Maximize Spell and all of his attacks being touch attacks, he can generally output a decently high DPR.

Against Orcus, it's not exactly a guaranteed victory. Generally, it takes 2-3 full attacks for Quin to take down Orcus. The trick is going first, then debuffing the heck out of him with negative levels to make surviving the retaliation a lot easier. Thanks to his +22 Initiative though (compared to Orcus's +10), this shouldn't be too difficult.

The weakness of this build is the ludicrous amount of spell points it costs to do...pretty much anything. Quickened (+4) Maximized (+3) Thanatopic (+1) Greater Admixture (+2) Ghostly Admixture (+1) Drain (+1) Taint Soul (+1) Time-Thief's Admixture (+1) Steal Time (+1) Stone Blade = 15 spell points. Stays a swift action though. Which is important if I want to full attack with it.

Then there's the cost of using all of my Mystic Combats, which can be set to free actions thanks to Time Shift (which will notably be nerfed in the upcoming Ultimate Spheres of Power errata). Thanks to the capstone, Time Shift itself doesn't cost any spell points, but everything else I use it with certainly does. Unbreakable, Quickened Reflexes, Mystic Adaptation and Swift Combatant are all things I'd likely be using from round 1, and in the case of Swift Combatant, something that might be necessary to spam (free action movement is amazing, even if it still provokes).

Still, I think it's a pretty strong and defensible build. Doesn't have the reality warping powers of a caster, nor the longevity of an initiator, but I still think it's one of my best late game martial builds.

Eventually, I'll make a level 20 Aegis, just to see how crazy it can get with the 3pp^2 (I.e. non-DSP, and non-DDS) support.