MArcomage

This mass discard is kinda obliterating. You sure this isn't rare?

Otherwise I suggest making the stock loss for both players a la Moonshrine

I had actually thought it to be a severe drawback, hence uncommon. But your comment showed that I wrote the card's conditions incorrectly.

The original intent is to have you discard YOUR uncommons and rares, not your opponent's. Because of such a severe drawback, I figured uncommon would be acceptable. [I've added "from your hand" to the card text.]

At 5 stock per discard, this card can deal an astronomical amount of stock loss. It should be scaled back. Discarding the cards of higher rarity from your hand isn't so terrible a setback unless they are replaced specifically with weak cards. It's especially not a setback if some of those cards are Illusion-gained rares from the opponent's deck that may be effectively useless in your hand.

Original stock reduction was much too high. Edited to make the card actually fair.

Now you can also lower the cost, 10 recruits should be fine (discarding the non-commons card is already an high cost), maybe it should discard only uncommons.

even less cost would be good. Because either way, this card is capped at -7 stock for your opponent (provided your hand is filled with non-commons), which is not such a good stock reduction, considering that you are ruining your hand.
And even -7 stock for opponent will be quite rare. Usually it will stay at -3 or -4, so my suggestion:

either reduce the recruits at 5
or make this card Swift/Quick
or make it a common
or have it discard your common cards instead of non-commons

Changed to -2 stock per card. I think it is somewhat weak even with this change, but -3 stock seems too strong, and making the card cheap on its recruits cost would make the card just too good in brigand decks in my opinion. Anyway, there's nothing wrong with somewhat weak cards--not every card can (or should) be stellar.