This mod looks really cool, but I have a few questions:

1. Can this mod be used on an existing save file, or would I need a fresh start?
2. Do the Fulgoran enemies respect Peaceful Mode and Enemy Expansion settings?
3. Can this mod be removed from a save file safely?

I really like the idea of this, but I'm worried about adding it to my current run and also about getting overwhelmed by aggressive enemies :)

1- yes, but they will only appear on future generated chunks
2-I think it does
3-Yes

Excellent! Thank you for the prompt response. I've not yet landed on Fulgora, so all chunks should be newly-generated. And if they turn out to be more agressive than I expected, then I can just turn them back off. This should work.

Strange, I ventured quite far away from my current base and haven't found anything... I even thought I haven't enabled the mod but it's clearly listed. Not sure for now, need to test later...

@Maxorio I second that. I've compared loading the mod on a fresh world and a world I had made without the mod prior. Unfortunately it appears that the fulgoran enemies never spawn in the latter world, even if you venture out really far into new tiles. Would be awesome if it did though! Would love to add this mod to a world I had already started

Fulgoran Enemies have a bunch of startup settings to determine their spawn and expansion behaviour. My guess is those are either not set or set to "nothing" if the mod is activated mid-save. I don't know of a way to tweak startup settings on an existing save file, else I'd try and see if it changes anything.

@Maxorio I second that. I've compared loading the mod on a fresh world and a world I had made without the mod prior. Unfortunately it appears that the fulgoran enemies never spawn in the latter world, even if you venture out really far into new tiles. Would be awesome if it did though! Would love to add this mod to a world I had already started

I can confirm that I don't see enemies on an existing save. It works perfectly on a new game though.

I managed do make it work on an existing save.
Using the mod Edit Map Settings.just open it and set both fulgoran enemies to the desired value (1 is default but not set)