Took a long time for figure out how/when to find the Doxy’s. After reviewing a couple of videos, found out that the Doxy likes to come up in the wee morning hours.
You need to ensure the “current outside conditions” is in the ‘dawn’ . If you’re wasting away at fighting other foundables, don’t, wait for the bow-and-arrow foundable and click on that.
It may be a horned serpent, a leperchan, or if you’re lucky, you’ll find the Formidable Doxy.
I usually found mine around the Minneapolis,MN USA area between 6am-7am. So there’s a lot of patience needed to find them, but they’re out there!