trigger for Spawning Creeps after an elapsed time in certain areas

[Oronuke]

Can someone plz explain or even better show me a trigger for Spawning Creeps after an elapsed time in certain areas as long as certain conditions remain true like I want only certain creeps in certain areas? I have an arena-based map I am currently working on and would greatly appreciate and easy yet efficient trigger/s.

 

[Rheias]

Untitled Trigger 002
    Events
        Unit - A unit Dies
    Conditions
        ((*Region() contains (Triggering unit)) Equal to True
    Actions
        Wait *real* seconds
        Unit - Create 1 (Unit-type of (Triggering unit)) for (Owner of (Triggering unit)) at (Position of (Triggering unit)) facing Default building facing degrees
        Unit - Remove (Triggering unit) from the game

A small location leak there... What it does is when a unit dies waits few seconds and then "revives" it (creates a copy of it).