I actually completed the "Ritual" thing, managed to kill Xvim, and placed the holy water vial into the radiant pool.
So far, so good.
But what next?
In the topmost level of the War Tower there are two (slime-covered) door for which a key is needed.
Where do I get this key?

After cleaning the pool and destroying The Globe of Essence ,you must go to the top level of the Officer Tower and kill capatin Pudu who's having a meeting with Vixeyn at that time. Get the key from him and then go to the top of the War Tower and use it to open the door from the left. You get to kill some goons here. Make sure you save after this battle cause it's the last one before Isair and Madae. Heal afterwords and climb down again to meet Buvai De'Naly or something,who's going to teleport you to Isair and Madae's chamber for the final battle.

[ October 23, 2002, 18:54: Message edited by: CauseMIN ]

I just noticed the Globe of Essence is still intact though I dropped the elvish thingie in the pool.
Maybe I´m mind blanked after slashing and ripping and malming through six levels but how do I destroy the Globe?

If you completed the ritual, then you can attack and destory the globe. Just hack away, it should not take much damage to destory it.

Edit: Also, if you have done everything else, then before you head to the top of the war tower to "meet" the half-dragon delegation, go through the rest of the hand and kill anyone left alive (slaves and good characters excluded of course). Once you go to the top of the War Tower that is it, so do whatever else you need to before heading up that way. Also, you do not have to kill Captain Pudu and his lady friend, you can get XP for convincing him to give you the key. It is not as fun, but you'll probably get more XP which was helpful to me since I leveled up right before the final battle.

[ October 23, 2002, 14:06: Message edited by: Grey Ghost ]