Playing Atlantica, it is important to know your goals when you are stunning. Your main enemy is the monk. He can use awakening to get rid of the work you worked so long to achieve. Therefore, he goes first. Make sure he is the first to stun, as he will be a nuisance if you do not.
The next target would be the main. The main can use an item Atlantica online Gold called a stimulant. This uses the main is turn, but it can get rid of the stun on any unit. This would be bad if he used it on the monk to awaken the rest of the team. So make sure he can not use it. Prophets, princesses, and exorcists will heal the mercs constantly, sometimes making the damage they take menial. And, while your main objective is stun, you have to deal damage at the same time.
Just go and stun whoever you want after that. Maybe that's the best you can do, in which case, you have just disabled 1/3 of the opponents team, which is very good. If you are feeling lucky, however, go for the perma stun. In addition, here is Atlantica online money service at low price.