Stun is easy to detect.
Event (generic unit) - unit is attacked
Condition (unit has specific buff) - unit has Stunned(pause) buff
Action - pick all units within playable map area matching condition, picked unit has Stunned(pause)buff
then use picked unit to do whatever u want with that unit (i think, or matching unit, i always forget)
Critical strike and evasion... now thats a tough one...