DragonChyld sent me a variation on my slither build made with Spelljammer, I'm reposting here with his permission. I revised his build for saves and skill point calculations. I'm pretty sure they're correct now.
This variant picks up craft trap and set trap. Less strength, more intelligence, less saves, should be around the same AB and AC.
I've been thinking of replacing the self-conceal feats for great strength feats. Base strength 17 on undying, +5 great str, +12 gear, +2 to str checks from universal contumacy or some other gear with Achoring I would give a final modified str check of 36, would allow the build to pass elysium str checks (dc 36 if a recall).
This is Flay's Slither Build using Spelljammer, Saves are a bit lower, INT is a tad higher, AB is the same, AC is 1 less but this build has the capability to use all of the custum trap kits in the game to their fullest effect
Ability Scores (before/after Spelljammer) Str 12 Dex 18/20 Con 12/16 Wis 10/8 Int 12/18 Cha 8
Pre-Epic Feats Bullheaded Weapon Finesse Toughness Iron Will Great Fortitude Weapon Focus Shield Profeciency
Epic Feats Great Dex I (Epic Fort must be Dropped for Dex) Epic Weapon Focus Epic Prowess Great Dex II (Again Armor Skin must be dropped) ESF (Search) ESF (Disable Trap) Self-Conceal 2
Rogue Pre-Epic Feats Defensive Roll Improved Evasion Crippling Strike Opportunist
Appraise 63 (Class Skill for Rogues and needed for traping cost) Bluff 6
Bluff 6 is entirely useless. Put the extra points in craft armor and craft weapon. With luck, with new gear you might reach 120.
Where can the documentation be found on traps? I'd like to see for myself.
I'm still a big fan of the intelligence artifact. The saves artifact might be a better pick, with that low will and demi penalties, you might find yourself gazed to death by narz.
Your modifications are based on my old build with self-conceal. The new spelljammer slither would have a final str of 17 (from great str instead of self-conceal). It unfortunately doesn't get as much benefit as the undying, but you'll still pass a bunch of str checks that you would fail otherwise. I think doing away with self-conceal and keeping hide is a good plan.
For the Human Half Fiend version, weapon choice cannot be club as it is a medium weapon and is not finessable by Medium sized toons. I just learned this the hard way - cost me an eye of vecna when I had to "do over"!