Look at the rush skill... notice that this grants you another turn immediately after you own. Use the <ApplyToCaster> tag and use that same initiative boost to yourself.
Secondly, look at hobble. Use the <ApplyToCaster> tag on this as well and set a duration of 2 turns.
Thirdly, look at the modifier DefendableDamage (The impale, spear attack, double strike all of these skills use it)
This will allow a character to attack and have a second turn to run away 1 space... or attack again. sort of a quick hit instead of a hit and run.
Althouth I haven't tried this you may consider the knockback ability done with the sheild bash and see the effects of this when you use <ApplyToCaster> tag. I'm not sure of the effects this will actually do.
***You could also set the attack to 0 for a duration of 2 rounds as well.*** that would prevent physical attacking.
***You could also add the silence ability for 2 rounds as well*** stop them from casting spells.