Actually it is a bit different - the mystic has an extra chance to be skipped when the enemy is choosing who to attack - if you are attacking a numerous group of enemies do not count on not getting picked. (the more monsters the greater the chance someone will pick you, regardless of the smaller chance) Warriors and Rangers have equal chances. (there was a misunderstanding on earlier explanation) Basically when a in the beginning of the battle a monster picks the mystic it is forced to pick again, hence an extra chance to be picked... However, the Guardian (one of the two possible specializations of the Warrior) has a skill that can attract attackers, hence saving the rest of the party from damage. (they are genuine "Tanks" after all)