Exactly! I keep thinking this is a) JUST what Shibisu would do; it's just like him to sneak in, and b) forget people's names/ranks, and c) trip over his own two feet, and d) it's apparently a regular if not just an act.
He's been MIA for a minute, they clearly finished their part of the map a while back, so he's had time to integrate... somehow. Although the LPB just arrived so he'd have to have moved very fast and been waiting at the teleporter.
But if you just imagined Lesoo in the place of the masked regular, it would be a perfect fit.
We're just going to have to fill in the blanks themselves - since we get so little.
More on this line of thought:
The Native One had 5 powers - fire, plants, rocks, water, crystal/metal (metal being essentially crystalline in atomic arrangement anyways...).
EVK, Khel, and Rak respectively have shown the first 3. We don't know if there's only one of each in the whole tower, but presumably so since the Native One split into 5 distinct beings. So the original 5 are the strongest, most-pure, and probably what we've seen so far.
So logically we have water and crystal left.
We also know the core of the Nest is the Frozen Waterfall, an unusually dense amount of suspendium. You could almost say it doesn't seem to be naturally-occurring.
Only Zahard and the LPB FH could barely access it as humans (or whatever ToG human equivalent they are). It took workshop tech to even access it.
Seems like it was created, but not by human hands.
Almost as if a giant that could control crystal created it as a fortress (later turned prison?) of sorts.
Almost.