Ok I have read all about surrounding Chaos with fluxcages and you have to use the firestaff to do it... The firestaff I have only includes fireshield in the menu, nothing like fuzing or whatever... ??????
You have to complete the firestaff with the powergem...there should have been a set of scrolls in the level where you got the firestaff that told you how to get it...
Apparently the Grey Lord spent most of his time trying to figure out which spell would release the Power Gem so it could be combined with the Firestaff...
Him messing up and getting the spell wrong is what caused all this trouble with "Lord" Chaos in the first place!
Although it is necessary to complete the staff with the gem, you can also use the bare staff - I remember doing that for a while, brandishing Firestaff and shooing Chaos around...