Question: In Alchemy, the rules for what kinds of cards can replace a trashed card are governed by the following, somewhat ambiguous wording:

> 
> Adding coins to a cost doesn't affect [potion] being in the cost or
>  not. If [potion] was in the cost, it still is; if it wasn't, it still
>  isn't.
> 
> 
> 

The rules then present an example with Remodel card. However, the Remodel card says:

> 
> Gain a card costing *up to* two more . . .
> 
> 
> 

The Governor card wording is:

> 
> Gain a card costing exactly one (or two [if you're the player playing
>  the card]) more.
> 
> 
> 

So, for the player who played the Governor card, it is clear from the remodel example that a card costing exactly 2 coins must be replaced by a card costing exactly 4 coins with no potion.

However, what about a card costing exactly 2 coins and a potion? If trashed, must it be replaced with a card costing exactly 4 coins and a potion? Or could it also be replaced by a card costing exactly 4 coins (but with no potion)?

Answer: 
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](http://wiki.dominionstrategy.com/index.php/Governor) out.
'Up to' means you can exchange a card with potion in the cost into a card that does or does not not have a potion in the cost, but you can **not** remodel a card with no potion in the cost into one that does. Remodel says "up to". You may Remodel a Golem into a Gold, or Remodel an Apothecary into a Golem. 

If the card says "exactly" like Governor, the card to be gained has to have the same number of potions in the cost, and the specified cost in coins. If you play Governor, you can trash University, and the only possible card you can get in exchange is Golem, as it's the only card that costs exactly 2 more than University.