Spawn triggers for fighting scene

I'm trying to make a fighting scene in a portion of my map where non-player controlled units continuously spawn in two locations (orcs and humans) and run at each other to fight. Like in the ending credits of RoC or FT (can't remember which, think it's FT) where they run down the hill at each other and fight in waves. Can anyone help me with this? Much appreciated.

I am a little new at this to be honest, so visuals help if at all possible.


Edit: This message and my other thread can be deleted. I figured it out. Thank you.

You mean like creep waves in AOS maps?

Oh nevermind.