Nice idea re playing without potions! How about this for a complete 'Chemistry' Expansion Set (Alchemy without thee Potions and Alchemists)?
- Herbalist - $2
- Transmute - $4
- Vineyard - $4
- Apprentice - $5
- Familiar - $5 + to buy this you must first reveal and discard a Curse from your hand
- Apothecary - $5 + to buy this you must have at least one non-Copper in play
- Scrying Pool - $6
- University - $6
- Golem - $6 + to buy this you must have a Gold in play
- Philosopher’s Stone - $7
- Possession - $8
Some comments:
- Transmute here is stronger than the weakish Alchemy card as it can hit Estates in turn 3, and synergises well with trash-for-benefit.
- Familiar's buy restriction might even make using a +Buy on a Curse worthwhile in an otherwise Curse-free board. Maybe.
- Apothecary is slightly weaker than the Alchemy card due to lack of potions. The restriction is mainly to handle 5-2 openings.
- Possession at $8 interacts with Swindler (though not as dangerously as Peddlar).
Okay, if you're going down that route, most of these costs are fine. But your buying restrictions on some just feel wrong to me.
Familiar: Usually you would buy this card as fast and play it as often as possible, ideally multiple times consecutively. If you had to have a Curse in hand so that you can buy it, it would be much later that you actually gain your first Familiar and, what's even worse, you need to pick up a Curse (waste a buy) to get a card that gives out Curses. So it's one less Curse for your opponent to gain - a huge deal in a two-player game. But at a cost of $6 the card would be too slow again.
I suggest a penalty each time you play familiar such as "discard a card from your hand" or even "discard 2 cards" to justify the cost of $5.I made a mistake in my thinking here. The card should be priced at $6 since it's obviously not intended to be bought in the opening turns.
Apothecary:
$5 is almost too much, I think. Again, why give it buying restriction that clearly anti-synergizes with the card?
I might give you up to four Coppers (not Potions) in your hand at best. So you might even get all your seven starting Coppers in your hand after your first reshuffle (but no Silver, so you cannot hit 8 on that turn), and you have no +buy, AND you might otherwise weaken your next hand with all those Estates. So even at a cost of $5, the only thing that really makes it better than Scout is the +card, and it's a terrible opening buy with 5/2. So it actually should be $4 (without restrictions) to be actually worth it. I made another mistake. The $-boost after your first reshuffle is significant and almost a guaranteed Gold, so it should be priced at $5 at a minimum.
Golem: There have been some good arguments here that Golem
might be just as good as KC. There are probably more cases when KC is better, but Golem has some advantages, too. The argument that Golem might play one or two actions that you didn't want is weak because you can easily construct your deck with exactly those action cards that you need (except in a Ruins game). So Golem should be priced at $7 and again have no restriction that doesn't have anything to do with its abilities.
EDIT: Whatever variants you choose, you should playtest them, and adjust when needed.