Just make sure the new potions are expensive or rare, otherwise you're just adding to inflation by trading a big SPS pool for a proportionally small DEC burn (and there won't be much incentive to load up on extra cards).

Honestly, I'd say just don't have the potions or perhaps only have them come from land, players should be dipping into the rental or purchase market to get the extra card copies instead of being able to constantly reload the cards at will.