That's an interesting use for Mind points and gives your game a lot of scope for character development though roleplay - which I really like
it works rather nicely with the basic game and I'd love to institute something similar in my own games, but my problem is that once you've used the extra magic rules from the expansions Against the Ogre hoards and Wizards of Morcar, it becomes clear that the mind points are not a measure of intelligence but a measure of the Hero or Monster's
strength of mind and thus his/her/it's ability to resist magical influences on their brain (in my houserules we eventually re-named the Mind stat to Will in an effort to avoid confusion)
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~The ravings of a single mad Goblin is bad enough, but such a power-hungry, malice-filled creature as Mortis can never hope to be understood~