Problem is most things I can think of that hurt REAL badly, where you may wish to pop a potion beforehand are magic damage, such as hellfire. VIT potion boosts defense to help with physical attacks, but MND potions only boost the main MND stat, and do not boost the secondary stat of magic defense: They instead boost the other secondary stat of healing magic. Granted, you could probably try to have the tank use a potion of piety and pray they get a partial resist, and have the healer use a potion of mind to help get the tank back up after... though the latter isn't usually as much a problem as the tank surviving the move in the first place, and that still puts the potions into the realm of "Highly situational"