ZSpellFiles. What is that? Well, you can find these files in /Data/Spells/ZSpellFiles folder directly in your game directory.
They contain a lot of information about effects and particles that is used in the game. And there is a way to use it to your advantage. You can actually edit them! Sadly, those files are compressed. But you may use a set of .txt files from Mac version of the game (example: SF_BeamExplosionCitadel.txt in Mac version (uncompressed), SF_BeamExplosionCitadel_txt.zzz in the main game (compressed)). You can get them HERE.
If you copy them and put them into your /Data/Spells/ZSpellFiles folder, then the game will use them instead of the original .zzz files, because uncompressed files have higher priority. And those files are actually directly editable, which allows you to affect how the game effects look like. You don't need to delete or replace .zzz files, just leave them where they were. They will be used again after you remove the .txt files from the folder.
Notepad++ is a very good program for editing text files, especially text files with systemized info or code.