Perhaps actually follow the tutorial
You can use bound to layout.
Or add a border (sprites) with solid behavior and make the ghosts bullet behavior bounce of solid
In event sheet:
Monster:is outside layout>>monster:set angle toward:Player.X,Player.Y
I have used bound to layout,but can not solve this problem.Monster will stop in layout border,not go to Player position.
And use a border with solid behavior,monster will go by reflection,not to Player position