It's random.
The only limit is that 3 portals can be opened per game, and none will repeat in that game.
You can read more about it here:
http://wiki.theamazonbasin.com/index.php/Pandemonium%5FEventBut, the thing that people commonly post is this:
Code
~Key Order~
H,T,D Order in Cube = MEPH BRAIN
D,H,T Order in Cube = Diablo Horn
T,D,H Order in Cube = Baal Eyes
Quote (iDeving @ May 19 2012 04:55pm)
hmm, u tested this yourself i assume
How do you test randomness?
But no, it's been verified by other people.
This post was edited by RaveTheGo on May 19 2012 03:01pm