Thanks, Mongotha, I've killed Hell Wyrm.

Took me 20 minutes to get to Sochen Palace from the nearest Teleport Crystal in Tchtiha Lands, also within that time I had to unlock the door.

The battle was long, but easy with decoy magicked on a character, and just constantly healing/Slashing will do you well. Equip power armlet on one character, and that helps a lot when it uses Judgement, overall it's an easy battle at level 88, it spanned for 1 hour and 40 minutes.