[Sever]

Heya, this is my first post to this funky site but don't let that detract from my info. There a several stages to battling Amelysan and the key is to control the flow between bouts. After each time you defeat her and she retreats back to her (your!?) throne, hang back a minute and make sure your party is fully healed, protected and positioned before you take on the guardians that appear. Do the same before you cut off the flow of 'essences' to the throne and you'll be showing this biatch who's in control.

As far as battle strategies go, I found that most offensive magic had no effect (even with lower resistance and malision) so I concentrated on an all out assault. Ignore all her minions that she summons as they disappear at the end of each round. Just arm your party with the best +5 and +6 weapons and use your characters combat skills (greater whirlwind, critical strike, offensive spin etc.) and she'll go down quick. If you find that her demons are killing you too quickly, try summoning a planeter/deva and some greater elementals and positioning them BEFORE the confrontation begins. Even simulacrum can be effective to buy a little time but make sure you cast it beforehand. The only time you want to stop attacking is to drink a potion or cast breech to remove her globe of blades spell. And before you know it, it's over.

To be honest, my party was mainly magic based and not suited to combat but this tactic still worked a treat so I can only imagine what a group of fighters would do to her. My party constisted of:

Me (Sorceror level 30) Staff of the Ram +6
Minsc, Flail of Ages +5
Edwyn, Dagger of the Star +5
Haer'dalis, Foebane +5, Short sword of the Mask +5
Viconia, Storm Star +5, Club of Detonation +5
Imoen, Angurvadal +5

Well, hope this is some help to you. Let us know how it goes.