feeblemind

[Isolrem]

The Feeblemind spell in DnD source reduces the target's INT and CHA to 1, and is permanent.

The Feeblemind in FK reduces the target's INT and CHA by 5 each, and lasts a very short time.

I do not know if this is a bug or merely an intentional variation.

[Raona]

The amount of reduction is actually variable, depending on the caster, but otherwise what you say above is true. I don't know the reasons/reasoning behind it. Does anyone? Is there an argument that it should be changed, beyond just matching canon, or an argument for why it should not?

[Selveem]

Same argument could be made for Blindness spell; it's supposed to be permanent unless properly treated magically. I think there's a few others out there, too.

As for arguments against it, in D&D Feeblemind is a very, very potent spell. It can essentially lock an Arcane Caster down . It's basically a one-hit KO with a fairly caster-favored odds. The spell is so powerful, in fact, that I generally house-rule against its availability in my campaigns.

In a fight, it can ensure victory. The only ways to protect against it is spell resistance (which as far as I know, Spell Resistance spell is not in-game and anti-magic shell offers very lackluster Spell Resistance [which I thought I bug reported, but I guess it's still not approved?]) which is even lower than it's lower level equivalent, "Spell Resistance," is supposed to.

Mind Blank SHOULD prevent it, but that spell is easily dispelled.