Can't think of any way to have enemies repeatedly spawn from one point without a script. Though with a script it is incredibly easy.
If you just want to cram a bunch of enemies into a single square so they spill out all at once, I think you might be able to do it by setting the entire screen except that square to be no enemies flags, then take the flags away either with combo cycling or screen secrets.
Edit: Okay another possible idea would be having enemies that always return and having a screen secret when they're all killed that direct warps to itself. The spawns wouldn't overlap so enemies couldn't accumulate on the screen, but it would cause the enemies to appear to "respawn"
Edit 2: I found it! After a bit of digging around possible ideas I found an instance of a genuine unscripted repeat enemy spawner. Downside is it will only work for a single enemy ID in your entire quest and will prevent you from using spinning floor tiles. The idea is you replace the enemy Spinning Floor Tile (Combo) with any other enemy. Then any time a combo switches to the Spinning Tile (Immediate) type it will spawn one of that enemy. So you can have a combo cycling setup that alternates between that and another combo and it'll continue to spawn the enemy each time. It's still probably better to just use a script than resorting to modifying ZC's hardcoded enemies, but I'm still amazed this works.
Edited by Moosh, 18 August 2019 - 02:38 PM.