How the fuck do I deal with them? I can't kill one as a rogue on my own. They drain all my wisdom at MOST with two hits since I have 10 WIS, and they frequently crit.

What the fuck am I missing here?

well easy way would be to have 40+ AC..
hard way is to park a cleric near you to spam restoration, their touch is con-save so having a lot of con helps too. basically buff with heroism and stuff to ramp up your fort. have a lot of con for the same reason. if you have other souces of fort saves use those too.

for pure rogue I'm not sure how you should win given dw finesse is bugged and you can;t flank the target 1 on 1.

Yeah I somehow doubt I can get 40+ AC on a level 10 rogue. It's just a horrible encounter.

The only consolation is that 30 days still haven't passed and I should be able to refund this if I can't get past those soul eaters.

properly built and buffed "rogue" has quite a lot of fort save and damage. even with finesse bug you should be abble to kill it. they are not tough and don't have a lot of hp. in my game even linzy could kill hers and she was alot more focused on support and disable than damage.

if anything alchemist can buff him through the roof as he can give out "personal" spells to others.

Two things:

First, this is an example of terrible encounter design, straight up. It basically requires either specific foreknowledge and explicit group optimization for the encounter, lots of save loading, or lots of cheesing to pass.

Second, though, given the above, I think this might legitimately be intended to force the players to utilize the difficulty sliders in the options, if that's intended to be required for encounters further on. I found that by cranking every difficulty setting possible down to the lowest level (make sure you do enemy damage last, at it resets with some of the other dropdowns), it becomes barely passable, even with my pure ranged support bard having volunteered her name without giving me a choice. Also make sure you remember your previous settings to reset afterwards (as desired).

I strongly suggest you pretend this encounter is intended to be passed only using the in-game difficulty options, like some meta Metal Gear style puzzle, because that's easily the most generously favorable interpretation of the encounter design.

this is not true though. it does not require anything special. just the ability to buff a bit and hit stuff with moderate efficiency. took me 2 tries just cause I forgot to prebuff on the 1st one. playing on challenging for my 1st run.

I've literally used all my cleric's buffs. I don't bring Octavia or the Half-orc, since they're pretty trash as casters. Have I missed a Wizard/Sorcerer companion maybe? Seems odd not to have a Wizard companion in a D&D game.

Octavia doesn't count since she comes gimped with 2 rogue levels.

Octavia is amazing actually. That 1 rogue level she comes with lets her become an arcane trickster, which is the most powerful caster in the game since they sneak attack with spells.
As a lv10 trickster that applies to all your dmg spells.
Also, Jaethal is immune to a soul eater's drain attacks, so just have her tank them.

there is so much factually wrong I'm not even sure where to begin.

1. reggie is one of the best built pregen companions out there. give him 4levels of dragon disciple at level 7-11 and he's good to go.he can easily go over 40ac while doing respectable damage.
2. octavia with wiz4/r2/at10/ek4 build hits 12 bab while getting lvl9 spells. alternatively you can go wiz4/r2/at4/ek10 for 15 bab and blast people with rays. caster level means nothing except for getting new spells. wizard gets lvl9 spells at CL17 after that all CL does is extra spell slots. only bad thing about her is her AI that spams acid splash even if you have nothing on autocast.
3. tristian is amzing caster as either single class buff bot or ecc3/empyreal sorc4/theurge10. add 3 more sorc after and 1 whatever else you fancy. you will get a swiss army knife caster. the better the later it gets.
4. cleric is pretty shit at buffing really. bard and arcane is where all the real party buffs are. what cleric does is fixing what harm has been done already.

Your builds will come in useful after at least 8 levels, since I'm currently 10, but thanks.

that is not true again. except for tristian that does have to sit in reserve till lvl9-ish. what I gave is final spread.
octavia by lvl 9 will look like wiz4/r1/at4 depending on what you plan to branch into at10 or ek10 at lvl10 she would've either taken 1st level of ek or be at5. either one of those has lvl5 spells
reggie would be ES7/DD3 with 36-ish AC 1 level till 4th level casting.

All right, made it past this dungeon only to be faced with an unhittable 48 AC enemy in the next one.

This shit isn't worth the frustration. It's like you have to know what to expect so you can build your companions around it and cheese the game. It's not even on Hard difficulty, it's Challenging.

Are we playing the same game? I've got no dispels on any of my mages AND she has saved every time I try to control her with Dominate/Fear/etc.

clerics get dispel as a level 3 spell. reggie gets one from his draconic bloodline. arcane casters get it too. to hit with disables you need a lot of casting stat+greater focus: enchantment+enchantment DC booster(there are several in the game) once you get rid of her protection spells she does not have 48 AC and dies pretty fast.