
Lastly, the Warlock's version.
I'm going to immediately note that the red lighting used in the image, though striking, is not actually accurate to what his room looks like in-game. Which is a bit of a shame; the Chosen each having distinctive color schemes would've more readily communicated that they have distinctive room designs as well as made them feel less same-y. Though I'm not sure whether the rooms being rigid per-Chosen was the actual plan or yet another result of the game being rushed, so it's hard to say what would've made internal sense for the devs to choose...
Regardless, it's broadly pretty similar to the Hunter's layout, with a central raised area whose ladders are indestructible High Cover, more high ground in the corners, and bits of bottomless pit forking off from the central high ground.
Unlike the Hunter's room, there is no part of the central high ground that is close enough to the Sarcophagus to trigger the fight: somebody will have to hop down to get things started. By a similar token, only Sharpshooters (Or a Reaper you took Squadsight on, I guess, but why?) can shoot at the Sarcophagus while standing on that central platform, making it much less useful to huddle up on it. It's still worth considering having some of the squad waiting there when you do kick off the fight, just... less great a payoff.
As the central platform doesn't extend out so far toward the Sarcophagus, you won't see the Warlock taking cover against a ladder when initially spawning. Instead, he tends to sidle up to one of the tall whatever-those-are that are close to the corner high ground spots. Whatever those are, they're surprisingly frail; a single Plasma Grenade is enough to expose the Warlock.
If you let him get a turn, he'll often run up to one of the corner high ground spots, whether to use the pillar for its indestructible High Cover or to hide all the way in the corner of the map while he uses Spectral Army. This latter bit can be really inconvenient if you've been keeping the squad near the central area -it's actually quite hard to get a line of fire on that back corner, so if you don't have really fast melee or well-placed Grapplers you may find you simply can't get at the Warlock at all when he does this.
By a similar token, when he respawns, he tends to end up using one of the indestructible pillars as his High Cover object of choice. Relying on being able to smash his Cover past the first spawn is a shaky plan; better to be able to reliably get at him with melee (Assuming he doesn't have Immune to Melee...) or Hail of Bullets or the like.
As an aside, I actually quite like the way Spectral Army interacts with this mission. In most missions, the Warlock using Spectral Army is prone to being a bit of a dud action that primarily serves to waste the player's time, which isn't even a threat in standard timed missions since if he's in a position to use Spectral Army he's by definition stopped the clock and won't let it resume until you've killed him. When it does manage to be something more significant, it's usually by virtue of the janky behavior of a Spectral Lancer ending up somewhere your squad can't see, with you having not gotten to see it because the camera was focused on the Warlock; a bit of a 'cheap trick' where you can't find an enemy not because the game meant for it to be hard to find but because everything happened to line up so they were hidden, basically on accident.
In the Stronghold confrontation, well, right away we have the point that the map doesn't offer much ability for Spectral Lancers to end up out of sight after spawning. I'm not willing to declare with certainty that it's
impossible, but it's certainly
highly improbable at minimum. Even better, it intersects in an interesting way with the pressure to maximize squad actions available for shooting the Sarcophagus, where the Warlock generates a bunch of bullet sponges and the straightforward thing of taking them out and immediately finishing him off will almost certainly leave you with barely any actions left to hit the Sarcophagus with. This naturally leads to mini-puzzles of trying to figure out how to either kill all the Spectral Lancers and then arrange to finish the Warlock in his turn, or arranging to kill the last Spectral Lancer in his turn and then finish him efficiently in your turn while most of your actions get spent on busting the Sarcophagus.
I'm pretty sure this outcome is basically a happy accident, but I still like it.
Something worth noting that's particularly pertinent to the Warlock but also applies to the Hunter and, less relevantly, to the Assassin, is that the Chosen don't do their normal 'inactive' behavior in their Strongholds. Even when they respawn out of your squad's sight, the music goes straight to their confrontation tune, and more importantly you'll never see the Warlock use Spectral Zombies. (I've never seen the Hunter use Tracking Shot, but remain uncertain if that's an actual limitation or if it's just the map's cramped nature and the pressure to chase after him ensuring he's never ended up in a position to consider doing so)
The music thing itself is kind of funny and probably should've been handled slightly differently, as the game simply does all its usual routines aside skipping the 'Chosen lurking somewhere' music, including stopping their personal music and playing the little triumphant sting each time you kill them again. Ideally you'll only have to kill them twice, but it's entirely possible to end up killing them four or more times, especially up on Legend where they respawn very quickly. It ends up accidentally-comedic, and they probably should've done something like switch to their lurking tune while reviving, or never left their confrontation tune until dead for the final time, or something. (The ideal would probably be giving them each a tune specific for the Stronghold confrontation that plays once they spawn until dead for good, but given the game's rushed nature that was probably never a realistic option)

Returning to gameplay, it should be emphasized that when the Chosen respawn they're always fresh, with all abilities off cooldown or having their charges set to base value, including that they can summon reinforcements right away. This is particularly important to keep in mind with the charge-based abilities, where the Assassin can use Mountain Mist repeatedly, and the Hunter can use Concussion Grenade repeatedly; it's easy to get used to the one-use nature of those abilities and stop being vigilant for them after one use, and then end up in a bad situation because they respawned and then used an ability you were thinking was unavailable to them.
But even with the cooldown abilities, it's important to keep in mind, particularly when you've destroyed the Sarcophagus, as this can result in them using cooldown abilities two turns in a row.
Fortunately, the Chosen overall don't have their balance lean very hard into powerful or dangerous abilities held back primarily by limited charges or long cooldowns. It could've been
very bad if, say, any of the Chosen had been given a no-questions-asked move to knock a single soldier Unconscious with one charge, and then you get to the final confrontation and two respawns later half your squad is out of the fight with not a lot you could do about it. So thankfully this resetting is not something you need to be hyper-vigilant against, especially if you're successfully doing the optimal thing of taking them out without them getting turns and smash the Sarcophagus without them respawning at full even once; managing such makes it all a moot point.

Narratively, there's bits and pieces I could poke at as weird or silly or the like, such as how it's slightly arbitrary you can't find a Chosen's Stronghold except by working with their adversary who starts out not knowing the location, but given it's a very good fit for the game and it's not got any
meaningfully problematic artificiality attached to it (ie there is no 'why can't I do this other, much less annoying option I should realistically have access to?' to the setup), I don't see much point to poking at such bits. There's clunkiness and unanswered questions here, but the closest to a problem is that it's never explicitly addressed why the Chosen don't teleport away once their Sarcophagus is broken and death is a real possibility.
Which... there's a lot of possible answers there. For example, they might not be able to; maybe their form of teleportation is tied up in their Sarcophagi, such that smashing it takes that ability away from them. Or we could focus on how absolutely awful the Ethereals are; I would readily buy that the Chosen are completely convinced the Ethereals would murder a Chosen whose Sarcophagus was smashed and then ran away, instead of getting them set up with a new Sarcophagus. (And would readily buy the Chosen are
correct in such a belief, for that matter) The Chosen death cinemas also make a point of having every Chosen look very ragged, and it's not entirely clear how we're meant to take this; you
can just go to the obvious thing of them looking ragged because you just finished shooting them to death for the final time, but it's possible that it's meant to be showing how much being killed, regenerated, and killed again back-to-back has screwed them up, where all the deaths and revivals have left them too exhausted to teleport out of here.
This isn't even getting into stuff like the Warlock clearly having emotionally-rooted reasons, where I doubt he'd think to flee even if the option
is available to him.
I'd sooner criticize the framing of you only having one shot to hit the Stronghold, which is never really given a clear explanation. Are we supposed to assume the Stronghold will be relocated, or that this is a specific access teleporter that will have its connection to their Sarcophagus cut? Even then, my issue isn't 'this is difficult to reasonably explain', but rather 'this doesn't seem immediately, obviously sensible, and we're just told it's so without a reason provided'. And... War of the Chosen got blatantly rushed! So it's entirely possible this is another casualty of that and nothing more.
So overall, the Chosen Strongholds, though they could certainly have had their narrative design stronger, they're not remotely bad on that point. It's some of the better stuff in War of the Chosen as far as that goes, honestly. To the point I don't actually have a lot to say about them in this regard -they're essentially competent, and it's difficult to say a lot about solid competency.
So on to another Chosen-related mission.