Kurgis attacks

[Quitschi]

When i saw him lately in a fight, i took a closer look at his attacks. Most effects are clear (like horror mark, curse or theft of life) but could not figure out what his attack "theft of reason does" its a ranged attack with damage stated as "special", so does anyone know it?

[Endoperez]

Feeble-mindedness, insanity, or something along those lines.

[Saulot]

Edi's Database shows it as magic-resistable feeblemind.