My Overlord is adamant that he purchases Overlord Cards in secret. I can't find anything in the rules that would lead him to this conclusion, but frustratingly there are only oblique hints to the contrary. I know he modifies his deck before each Quest in secret. I'm strictly talking about the Spending Experience step of the campaign.
I tried asking FFG but it's been a week and I didn't even get a confirmation that they received the question much less an answer.