Attempt to add new spells and skills.

What do you mean by "what to read"? I ran your files, and I got a gray spell in the book, but there's no way to apply it. After playing around with it a bit, including adding it to EnumEntries and other places, nothing changed at all.

I understand about 97 too, but for some reason it doesn't work.

That's right - CUSTOM5 is a script-based spell that's used in the field; it won't just run on its own... it needs the corresponding script content!

As for SPELL_VASIK, it consumes mana when applied, but nothing happens, because it seems that SPELL_VASIK is launched, and the handler tries to find code for it, but there isn't any... because there's no reference to the SPELL_VASIK subroutine in the .exe... i.e., for any non-existent argument, some procedure DO_SPELL returns false and jumps to some C3h code (return, i.e., a return occurs to the calling procedure).