Text : When Revealed : Attach to a hero you control and exhaust that hero. (Counts as a Condition attachment with the text: “Limit 1 per hero. Treat attached hero’s text box as blank, except for Traits . Attached hero cannot ready.”)
Text : While there is a hero card in your discard pile, Prince Imrahil loses the ally card type and gains the hero card type.
Imagine Caldara is in my discard pile ... Looks like an infinite loop ??? Ally then Hero then Ally then Hero then Ally etc ...
So because i don't want to have a game blocked by this loop of passive effect :
1) Prince Imrahil stay ally
2) Prince Imrahil stay hero
3) Prince Imrahil isn't a valid target for this treachery due to generation of an infinite loop with no ending