When we arrived at the Radiant Obsidian Basilica, we saw the place truly had been corrupted. The once great structure had partially collapsed, and was covered in muck and other disgusting things. The stench was awful. We snuck our way in through the gross waters, eventually coming upon the door to a larger room. We spied sentries on the other side, but Volt was able to silence them quietly. However, after they were dispatched, we were attacked by giant flies, and eyeballs appeared in the muck flinging poisonous filth at us. Luckily, we took care of those without alerting anyone else in the building to our presence.

After passing the great room, we saw the majority of the people were in a mess hall. The foul, corrupted acolytes were quite surprised by our sudden appearance, and we slaughtered the whole lot of them.

Volt found a trap door in the far corner of the hall, which we descended. It was less dirty here, and we descended a winding staircase, eventually getting to a room with an altar on the far side, separated from our side of the room by ominous still water. We determined the water was quite poisonous, far too deadly to try and swim through. 

A giant eyeball appeared on the wall in the far side, befuddling me for a few seconds. When I got my wits about me, I saw Volt and Isha had managed to get across. Since I couldn't join them I tried firing arrows in support, but then a giant muck creature rose up from the muck, blocking my shots. I would later learn it was an illusion. Eventually, the god who had taken up residence here was defeated, and we managed to recover the dagger.