Thanks a lot. We have found everything but aren't sure how to do it correctly. I'm fairly new to hex editing. Can you show us what to change exactly when we want to modify the type of a spell. So that for example blind only lasts for 2 round no matter the spellpower.
There's no universal solution. Maybe this thread would be of help, as there you can find many examples of how to make small patches (check out the "4. SPELL" section particularly). Still being technically hex-editing, writing such patches requires some knowledge of assembly language.