Charm, Sleep, Fear, Confusion

Writing some spell lists, I've come to think about D&D's mind-altering spells in particular. Charm, Sleep, Fear, Confusion. 

They all have the potential to be encounter-skippers. Then, why choose one over the other? 

In the rules the differences are subtle: Charm might give you a temporary ally, so does Confusion by making an enemy so confuse that attacks itself or its allies. Sleep might affect more enemies. Fear makes the target flee, carrying away all treasure they might hold.

But in practice, rules as written, they speak more about how the enemies act than on how they do feel. For example: by casting fear, an NPC will never react to fear by trying desperately to befriend you, like in a charm spell (so you spare his life) or channel the fear attacking, but awkwardly, like in a confusion spell. RAW, they will always flee. So the spell effect is not as much about what does the target feel, its more about what they physically do.

So, a wizard learning Fear in wizard school, dreaming of the day in which he will subdue armies at his feet using magical fear, will be dissapointed because fear will only send them fleeing from him,

I'm thinking on having all those spells somehow mixed in one. Lets call it "Ensorcell".

When you cast it, you change the reaction of target NPC 2 steps up or down the Reaction Table. That is the effect. It's the GM who, depending on the reaction and the situation, describes which is the magical effect who caused it. Lets say that the Reaction Table its like:

A goblin who is attacking you (Immediate Attack) would be hold for some turns (confused). The GM says if its because of fear, daze, tiresomeness or maybe he is tripping balls.

A hostile one (roll of 3-5) would retire its attack completely. Maybe he is asleep or just lost his will to fight. He might not get in love with you, but will be opened to negociation.

If the monster is undecided (6-8), then you have the chance to make it your pal/waifu, as a classic Charm spell.

Possibly you can increase the power of this spell somehow, to make an Immediate Attack become an Enthusiastic Friendship by casting it twice or whatever. 

Now, I can imagine the same wizard in wizard school, memorizing lots of different theorems and tricks to be capable to ensorcell enemies someday, and adapt his spells no matter the situation. 

The bad part of this approach is that, when cast on PCs, it lacks guidelines on what should happen. The GM should interpret it based on the shown attittude of the PC towards the caster and interpret it as it was a reaction roll.

Monsters that normally cast effects on PCs, such as sirens or vampires, still work normally casting Charm or Fear, and should affect PCs just as they do in classic rules, no matter what is their attitude. They are monsters after all and work outside the PC's rules.