Mordheim: City of the Damned

This should come with natural play, but if you want to speed it up, in order to stun enemies you have to crit them, then they have to fail a stun check. To increase the likelihood of critting, you can raise the accuracy stat of your warriors. Once you have someone stunned, just have everyone focus him until he is put out of action. This should be unlocked well before you have played a warband for a year.