It varies a little depending on luck, but Extinction creature spawns are set to be around a 10% chance in their listed region. Clearing other mobs will definitely help. They will be added to some of the future caves as more common encounters, first of which was the southern snow biome cave for managarmr, enforcers, and scouts.

Thanks for that fast answer ! I will start cleaning everything :)

Well after hours of clearing the jungle around the green obelisk with no luck at all, I can certify that they are quite rare indeed ! No gacha for me it seems :( If you have any trick or hint, I'd be happy to hear it.

Originally posted by Syanlin:

Well after hours of clearing the jungle around the green obelisk with no luck at all, I can certify that they are quite rare indeed ! No gacha for me it seems :( If you have any trick or hint, I'd be happy to hear it.

Gachas seem to be the roughest one to find from the feedback I've gotten so far. Aside from the area near the green obelisk, they can also be found on the small tropical island to the east of the volcanic island. For some reason they seem to show up there more frequently even though both areas use the same spawn parameters.

Thanks man, and thanks also for the map it is really nice. I also appreciate a lot that there are notes on the map, something most player-made maps don't seem to have.