Why are there random map bosses in my map? Petrified suddenly and killed

I just got petrified and died with no possible outplay in a cemetry map because the pertify boss from sulpher vents or whatever map is just walking around as if it is a normal monster. I am levelling an alt so no scarabs, or anything affecting the map, how do I stop this from ever happening again? It's awful. I tried googling "random map boss in map" etc but cannot find any info. Anyone know what is happening? Thanks!

Other map bosses cannot randomly appear. You're using something that makes them spawn specifically.

Do you have "Destructive Play" allocated on your atlas tree?

If it is actually destructive play then I would still keep it on just because that boss is really only dangerous if you don't expect it and now you do.

It's probably the note "Invasive Adversaries". It adds a 10% chance that a pack of monsters contain "difficult and rewarding" monsters to ur maps. Those difficult mobs are the same as in T17 maps afaik. So it's random map bosses as a regular monster type.

Must be invasive adversaries. Not using destructive play. Cheers!