What's your native language?
In my signature you can find a simple Damage Over Time (DOT) system. For Slow/Stun use "Pick Every unit in range matching conditions", create the dummy caster that will was slow or stun on the unit (Unit - create unit), add an expiration timer (Unit - Add Expiration timer), order the caster (Last created unit) to cast Slow/Stun on "Picked Unit" and you're done.