I've never done a challenge run. I find a regular run challenging enough. I wonder why the four White Mage party is considered the most challenging though. Don't get me wrong, it sounds hard, but four white mages means four people with healing abilities and they still can equip some decent weapons. On the other hand, four black mages means no party members with healing abilities, no party members with good defense, and no party members that can equip decent weapons. Granted, with four black mages that's a lot of spell slots worth of destructive power, but they're gonna need to use those up even more than usual, because it's basically all they have. It seems like four black mages would be harder to me, but maybe not. Also, four thieves sounds pretty rough.