845a8e7d_ption___MuOnline_Pentium_Tools__Why_to_edit_
[File Location] \Data\Local\ [File Name] ItemSetOption.bmd [Description] Configuration of Ancient Sets that in the game(For each set what options available with what value) [Why to edit?] 
If you want to add more ancient sets or rename sets names. You need that server side itemsetoption.txt will be same(after editing you can exports for server side file)
MuOnline Files Description - MuOnline Pentium Tools
Why to edit?