I didn't check your last file but there is a typo in the previous one: RADGSV.spl (Doomguide's Save vs. Necromancy Bonus) is wrong. You should change opcode #326 with #346 (Save vs. school bonus) and set parameter2 to 0. ;)
Thanks for the link. I was able to locate mschool.2da, but IDK where to input the Necromancy code. I can see no field labeled as Special or something like this. This image is from the amulet. I can see the P1 and P2, but the Necromancy code (25269) is nowhere to be found.