How do I Start a "system every X second" when you are in---

I currently have a function that spawns creatures in a room with sound on spawn,

it currently looks like this

"Every X second, function call Creatures"

"Function on Creatures...."

Is there a way to start the System "timer" when the player colides with a certain object?

(And have it paused when the player haven't entered the room yet?)

Use the Timer behaviour.