From what I can tell, the Heavy Zerrikanian Fire Scorpion card is only available from a merchant in Lindenvale (link here). I found the guy, that's not the problem. But I can't talk to him. The prompt never even pops up. This is the guy (not my picture though). Anyone have a solution to this issue?
I had to combine a couple methods before I was able to talk to the merchant. I'm guessing I just had an extra buggy game, since I talked to a couple people who didn't have an issue with the same merchant. Basically, I saved before going to him, then meditating for a little bit, and finally just decided to run around for a minute or so and when I came back, I could talk to him.
I can also confirm this is where the Heavy Zerrikanian Fire Scorpion card is.