In Solstheim, there was a part near the tower where the player can't be controlled and forced into an ai package. You can't control the player for a while and he will be like the others mindlessly building the tower. It is possible for the player to be affected by the illusion spells, but the spells will need scripts attached to them that works only specifically for the player while still retaining their original function for using on npcs. Turn off the player's control, and put him into a package that does what the illusion spell intends, then turn on player controls back after the duration. The problem would be, if the player gets hit by an illusion spell, it's like the end. Once the spell expires, he can easily be hit again. It would get annoying not to take control of your character anymore. So, do you really want something like that? I think the idea of changing the look of npcs around to look like your enemies for frenzy spell is more feasible. You don't know who to attack, so you attack everyone. For fear, how about your health and damage is reduced to 1, so obviously you will be afraid to fight.