Lethice’s Stronghold

The first part of Lethice’s Stronghold was added in the 0.9.0 update and can be found while searching the High Mountains. This location cannot be found until finishing the Deep Cave dungeon - the third dungeon in the game's main quest. After arriving at the Stronghold, it can then be found in the Places menu. So far, there are only 4 known Bad Ends.

This is the haphazardly made map

Mirror Room

In the Mirror Room, you can either put on Glasses or Leave. Putting on the Glasses results in a battle with your Doppelganger, a fight which is extremely difficult, as you have to use uncommon methods (special attacks like the bow or dragonfire) to be able to land a hit consistently before round 6 (the final attack round).

Hall

In the Hall, you will encounter a horde of Basilisks. If you try to move past them without Laybans, you will be crowded and captured, and eventually be brought to their king. Trying to go back after running past them with Laybans will result in the same thing. After explaining that he knows about you from your adventures, you can goad him into a fight by choosing the 'Taunt' option. Choosing the 'Run' option leads you to a Bad End.

Tentacle Garden

The Succubus Gardener can be fought in the Tentacle Garden. The best way to beat her is by using Tease and casting Arouse after having brought her down to 50% health, where her health will be restored to 100% when she takes enough damage (~50%). The text of this healing implies that it leaves her more susceptible to lust. Choosing to fuck her after victory will result in a Bad End.

Statue Room

A giant statue can be found here, which when beaten drops a Lethicite crystal. Its use, as stated by Fenoxo, is purely as a combat challenge, being a massively difficult foe at level 22, dropping a large portion of EXP. After you defeat it, it crumbles to pieces, and you find a Lethicite (not Marae's Lethicite) nearby, glowing a purple color. If you do not defeat it, it leads to a Bad End where you are crushed underneath the Statue's hammer.

Barracks

The Centaur Herm can be fought here; a massive, highly corrupt centaur that has the ability to heal herself and orgasm to relieve lust. Fucking her after defeating her does not lead to a bad ending, just a satisfying sex scene.

Entrance to the Throne Room

In the room that contains the throne entrance is a locked portal, which you can't understand. Currently, the only option is to continue on your way.

Exit - Cable Car

As you exit the facility from east side, you run into the cable car. If you chose to give the incubus the book in the demon factory, he stops your leave, demanding a toll. The champion has three options here. The first is to pay 500 gems, though the incubus comments he was only joking about the gems, but still accepts the toll. The second option is to suck the incubus's dick. The third option is to fight him.