The lake
This next 'hall' confused Lumen as he had already deduced the pattern that this area was following and was 99% sure that the third hall would be something like a fully intact and decorated hall or something like that.
Instead it resembled the familiar looking environment of the cave that he had spent the last 2 weeks exploring, except for the fact that this hall was filled to the brim with water that upon inspecting, seemed to be bottomless...
He focused his gaze and scanned the area as he spotted a few parts of the floor of this underwater lake that weren't underwater as there were several platform like rocks dotted about, starting at the entrance to the hall.
He took a closer look at these platforms and concluded that they extended all the way to the other end of the lake, with three identical rows in total sitting only a metre apart from each other.
His worst fears had been realised...