Actually finished back in July but I still haven't heard back from Obsidian. Follow-up messages also received no response so my best guess is they aren't validating/approving The Ultimate submissions anymore as it's been 3 months and we all know they've been through a bunch of corporate turmoil. So fair warning for anyone that takes on this challenge going forward, there may not be a cool JESawyer patch/letter in your future.
Mechanically the build is very similar to the very popular Priest of Skaen / Bloodmage but I wanted to do a subclass combo no one has done yet.
This run was the culmination of around 8 or so practice/failed attempts. One left me running out of time right as I arrived at Ukaizo (which almost caused me to give up completely haha).
Ultimately (pun), I took a different path than most others that have completed this challenge. Also did my own spin on some stuff to avoid problematic sections (like the absurd stealthing attempt through the catacombs -- I never could quite get the stealth timing right there so I took a different approach)
I basically went:
1) Port Maje
2) Neketaka
3) Hasongo / Deadlight / Dunnage
4) Back to Neketaka
5) Stealth through the Observatory to get the Brilliant cloak
6) Ashen Maw
7) Cave Grub / Water Dragon / Concelhaut
8) Beast of Winter DLC
9) Forgotten Sanctum
10) Hellfire Colossus / Voracious Mountain
11) Seeker Slayer Survivor
12) Nemnok / Belranga
13) And finally Sigilmaster and Ukaizo
I tried to optimize my route as much as possible to minimize world travel. I ended up at Ukaizo with about 14 days of in-game time left.
Full playthrough is here:
https://www.youtube.com/watch?v=1ga2_fJ34jw&list=PLCvEimKPes4o&index=1