I see. Well, if what you say is true, then now is the time to strike. I believe Athrikus resides at the top of the tower. Be careful though, he is surrounded by many powerful warlocks, much more deadly than the ones you faced before.
With the death of Athrikus, I hope that the demonic forces in this area will be driven back. I have no doubt that they will regroup and return, but then we shall be even more prepared to meet their threat.