I am pretty sure I have this right, but I am just checking. On a mint, you "trash all treasure cards in play". I played a board last night against my dad where there was Golem, Familiar and Mint. I decided to get the potion to pick up Golem and Familiar and then I wanted to get rid of my potion. So then I had a turn that added up to enough to buy a mint, but I had a potion in my hand. I thought it should be fine to put the potion "in play" even if I don't buy anything with it, but I wasn't quite sure. My dad later played a terminal silver action and 4 coppers to buy a mint so he could trash all those coppers even though he only needed 3 of them. In the rules it says you can put all treasures in play and buy anything of equal or lesser value, so I think this is fair play, but I just wanted to make sure.