Endangered Monsters

Correct me if I'm wrong but they're just activate-on-pickup Use items, aren't they? After all, we have had CPQ pots being given out before (All-cures in the Raven shop - don't know if it's still like that, though)

They are, but if you had one in your inventory (somehow) and clicked it, it'd probably just give you the buff. Cards are also marked untradeable so you couldn't drop it and pick it up. I don't think this would happen even if it did work because cards are only helpful for the first 5.