In the Tamurkhan book it states that nonmagical weapons suffer a -1 roll to wound K'daai Destroyers and Bale Tauruses. How is this rule interpreted when a to wound roll requires a 6 to wound. Simply put, do the attacking models simply can't hurt the monster if it has this rule against magic weapons? I've played it that '6' does wound when it is the only way to hurt one of those monsters, but what is the right interpretation?