Did a little exploring myself in Pandemonium the other day.
Interesting to note the Timid Spectral Scourge ( unique in Pandemonium ) spawns a portal to a boss room.

- Picture courtesy of Spherana
According to sources there are 2 playfields for Pandemonium: A Normal and a Boss playfield.
This probably works the same as Innersanctum. Kill a boss to spawn a portal to the next level.
A guildmate is hopefully gonna' get me some pictures so I can show you all what it looks like it

Willing to bet, once pwn'd this boss drops the Pandemonium Armour.
AND
Welcome to ACE camp Take II

10+ guilds fighting for 1 unique. FFA anyone ?
P.S. Hits for about 6 - 9k without RRFE ( or SL equivalent )