OK, so I've done a bit more scouting of Curious LT.
The sin spawns seem to be Pride -> Wrath -> Lust -> Sloth -> Gluttony -> Envy -> Greed, repeating.
This actually provides an interesting depth because before you tackle a high level monster, you can kill some popcorn to cycle through the more difficult sins.
Some thoughts on the sins:
Pride: Easy kill unless you're relying on resists - try and use your piety before fighting a high level one.
Wrath: They seem to have a number of DPs corresponding to levels, which makes them very difficult. Self-cannon shenanigans with CYDSTEPP should be possible, though, since they have 500% knockback. Don't fight them at high levels unless you're a caster, though.
Lust: Straightforward easy kill. Also, you can farm them for free piety as they spawn Lekon's Chosen, which give you goat piety. If you find BURNDAYRAZ early on, it's worth it to kill a few popcorn (or level 2s) just to get a Lust, at which point you can use BURNDAYRAZ and kill the spawns (you'll get 2 spawns per cast of BURNDAYRAZ because of the burning pop. This means you get 4 piety per 6 mana, the most efficient way to get piety through exploration in the game. Add this to Mystera, say, and you're really rolling in piety.
Sloth: These enemies suck. I would leave them alone altogether. Spawn these from undead popcorn so you don't miss out on the bloodpool, and just leave them alone, unless you have a Weakening cure. It might be feasible to fight them with a tanky low-damage build, but such a build struggles with literally everything else in the dungeon so you shouldn't bother.
Gluttony: Straightforward easy kill. These guys are probably the easiest ones to kill, as long as you don't regen fight. Treat them as Serpents or Trolls.
Envy: Bad unless you have Soul Orb or are a melee specialist (which struggles here, as in most EE Vicious). Ideally spawn these from undead so you don't get an acid pool. Corrosion cure required, but you should be carrying one anyway if you're using The One Horn...
Greed: Not terrible once you see it coming. Don't ever kill a popcorn to spawn one of these. Good for high level kills, but make sure you pour all your health and mana into the spawning enemy to avoid the insane stats they'll get. Especially mana.
If I were to give any criticism, it would be to either remove Weakening Blow from Sloth, or at least reduce the Riposte to 50%. As it is, they pretty much are completely untouchable because Riposte is so strong, and has Weakening Blow attached. Even if they only had Riposte 100%, they would already be very difficult enemies for most builds, but Weakening on top of that just makes them completely untouchable.
I have no notes on the boss yet. If the Vessel has the same gimmick as before, it looks like he's going to be getting a full heal from his goats, because I don't see a reasonable way to kill any significant amount of the Sins. Also, you lose a lot of blackspace that you normally get from the goat transformation since you can't safely explore it without losing all your health/mana. Therefore it's best to try and spike him down to when he gets the refill. Cursed Cutlass, resists, Life Steal, and maybe Binlor are necessary to erode his huge resists after he refills. An alternative way to get around this is using LEMMISI or BLUDTUPOWA, but I don't see how I'm supposed to kill any real amount of the sins without using far too many resources...
Oh, by the way, I don't think I've mentioned this, but this entire seven sins idea is very cool. I'm excited to play through it for real to see how it actually plays out!