Knockback trigger, how?

I was playing a few maps and noticed quite a few abilities having "knockback". I tried to replicate it, but didnt work out the way i planned :( . Anyone have this made? or can tell me how to make it?

event
ability is cast
condition
ability = knockback
action
move instantly target of ability being cast to point offset by (distance) towards angle between casting unit and target of ability being cast.

Voila.