Anytime a character used Pot of Greed, they would explain what the card does
And from there, anyone with a TCG they enjoy knows what happens next
Even within the rules of fan-art I listed above: people buying it know theyre buying a proxy, a replicated card (at least, assuming its not someone trying to hock a proxy off as being authentic) the fact that it does use authentic artwork is tricky, and maybe the most grey of greys involved proxies dont interfere with the rights-holders from selling cards because, well, the rights-holders dont get ANY money from the secondary market to begin with
Donna Noble (his companion at the time) has, in desperation, touched the severed hand of the Doctor, which is at the time filled with regeneration energy (which is itself all a long story)
In particular, I was hoping to pull one of two sorceries, two enchantments, and one legendary artifact