[Quitti]

Insane just means that the commander has a chance of doing random things and not listening to your commands. It's pretty much identical to the Shattered Soul of tartarians, except that insanity can't break labs/temples if I recall correctly, whereas shattered soul can.

Easiest way to see insane commanders is to play with/against LA R'lyeh, their dominion causes it to most commanders in the game.