Not having 20-30% WTs is your mistake not overpowering. Also you need a group of rogues for that and as I said - don't do MS at the beginning of the war and take care of the enemy's rogues. The problem of mystics is they don't want to spend mana for anything else than MS which does nothing to protect them from rogues. With the superior wpa mystics also can stop rogues they just don't want to use it.
EDIT: if you war against KD with 10 rogues almost nothing can stop them AW-ing your mystics. But this is called take one for the team. Just like attackers are being chained and destroyed.