The Decrepit Altar on the Nameless Isle in the cave east of the Temple of Rhalic, has a mysterious, yet important secret in Divinity: Original Sin 2. If you’re wondering what’s the deal with the Decrepit Altar and how to solve it, you’ve come to the right place.
The Troll that guards the cave
In front of the cave that leads into the Decrepit Altar, you will find a troll guarding it. You can choose to initiate combat or try to pass a speech check as you convince him to let you through.
If you choose to fight him, you should mind that the troll has the Troll blood ability, making him regenerate thousands of health per turn. Either burst him down quickly or use one of his weaknesses against him to disable the regeneration.
How to get past the Decrepit Altar
The Altar will ask for blood, which might prompt you to cast a spell, like Blood Rain on it, only to realize that it is no use. What you need to do is equip the Cowl of the True Sight, preferably on your character with the highest intelligence level. Using the Cowl of the True Sight on the wall behind the altar will dispel the illusory wall and allow you to enter the room behind it.
If you are having trouble with the dispel ability, make sure to use it on the wall and not the Altar. The ability has an area of effect, so the cone needs to hit the wall.
An alternative way of solving this riddle is placing the head of Bishop Alexander on the Decrepit Altar, if you have killed him (and not eaten his head which you should absolutely not do in this case). After the illusory wall disappears, you will still be able to take the head back with you.
The Black Ring Encampment
Once you pass the illusory wall, you will enter the Black Ring Encampment. Walk down the ramp into a larger room and you will find the Sallow Man. Now the interaction will depend on your party composition (if you have Lohse in your party, combat will be initiated immediately), as well as the choices you have made before and your own wishes.
- You can either fight the Sallow Man as requested by Bishop Alexander if you have sided with them and against the Black Ring.
- Or you can fight and kill Bishop Alexander as requested by the Sallow Man if you have sided with the Black Ring.
At any rate, revealing Bishop Alexander’s head to the Sallow Man (which is why you should not eat it) will complete the quest and make the Sallow Man give you a reward. If you did not kill Alexander and have sided with him, you will need to initiate combat and defeat the Sallow Man.
If you chose to engage the Sallow Man, three Black Ring members will join the fight. Beware that the Sallow Man himself will resurrect at least once after defeating him, meaning you will have to kill him twice.
Head deeper into the cave and you will eventually find the Sallow Man’s war room. There is an ornate chest that contains a piece of the Swornbreaker, more specifically the Haft of the Swornbreaker.
You should beware of the fact that inside the Sallow Man’s cave, you will also find another iteration of Windego, which you will have to fight and kill. It will yield no EXP but trigger the quest “Mercy is Power”.
While this secret behind the Decrepit Altar is optional, you should mind the fact that the Haft of the Swornbreaker will net you a powerful weapon if you manage to forge the whole weapon, as well as the possibility to use it in various quests.
Also, there are other quests that can be finished in the room of the Sallow Man as well as the extra encounter with Windego.
If you want to find out where to get other parts of the Swornbreaker, check out this guide: