I only tried changing SkillEffects and/or PotionEffects, copy original effect, change resistances on CC spell like Fear, next i renamed Fear to XXFear and replaced original Fear (in spell properties) to XXFear, its something like new spell but not exactly new. Image below will show where i made changes (not all at once but with random combinations).
[Linked Image]

In game version 3.0.146.969 tests showing only icons like Terrified but no true effect, btw before last patch this method worked without problems, targets with full physical and/or magical armors were terrified.