Replace highest cost card from opponent's hand with Reuse the rubble
N = total cost of the replaced card
This is a strong discarding card for already strong Tower+ decks; suddenly they wouldn't necessarily want cards like Sheath Your Swords, because they could hit all the opponent's really dangerous Attack cards, or even Sabotage, while also gaining much-needed Bricks at the same time... when they already want to convert Recruits into Bricks at every opportunity.
And on top of that it gives a card more useless to most decks than Wind rather than just discarding (like Sphinx, another discard-and-resource+ card does, and that one is certainly less forgiving with both cost and requirements of getting Resources!).
I would put this at 10 Gems / 10 Recruits in cost, and then on top place some sort of caveat or requirement on it; like make it capable of hitting your own hand by accident by removing "opponent", or place a rarity-related or keyword-related cap on what it can target, or make it so you only get the Bricks+ at all if your hand already has a card type you don't see in Tower+ decks much.
Also, from a thematic perspective rather than a balance one, it feels really weird a thing that works by turning things to stone is exactly as effective on on things already made out of stone as things that aren't. I mean, this card serves as a counter against big Unliving cards or even an opponent Tower+ deck's Pyramid or Fortified Castle just as well as anything else.
Does this Medusa have the power to just steal stone things of all kinds on top of being able to turn things to stone? It's seems like that more-powerful interpretation of the monster deserves at least a rare status, maybe Rare and Forbidden / needs-summoning-card.