Oni Dungeon.
Right in the middle of the dungeon's vast subspace, there was a huge pyramid-like construction. It had various floors and four sides. Each of the sides featured aptly distanced steps that could be used to climb the pyramid to its top-most floor.
This top floor only featured a giant open hall. It was called sacred telesterion by all the monsters that had occupied this subspace.
The telesterion was about 500 meters long and 100 meters wide. It also had a sturdy ceiling that was supported by the equidistant giant pillars, which boasted glowing runic details.
There was a raised platform at the far end of the telesterion. It seemed to serve as a throne platform because it had a throne at the end of its steps.
There was a humanoid monster sitting on the throne atop this telesterion. He was looking at his audience with mild disinterest in his eyes.
