When Governor and Alchemy cards are in same game, how does gaining a card for trashed card work?
It must have a potion. The rule states that any time any cost is increased, the potion quantifier stays. Since the card you are trashing has one potion in the cost, the card you pick up also has to have one potion in its cost. For more strategy with this card (albeit not help with this particular question!) check this out.