Sorry for the delay. We actually spent some time talking yesterday about this very card, so I’ve only been able to get back to you now. Thanks to you and another poster on Kickstarter, we ended up changing the card back to something closer to what it used to be earlier in our testing.
Here is the new text:
“Make target hide 1 card from their hand under this card. They can discard this card at any time to take the hidden card.”
So, going with this new text, there is still the question about how soon the target can or has to put the hidden cards into their hand. Because “they can discard this card at any time,” the target (you or someone else) can wait to pick the hidden cards up until a later time.
Also, if you remove Stash, you must take the hidden card(s) into your hand (triggering Overload if you have 10+ cards). Only after can you play them (if it’s your turn). You can’t decide that you won’t put those hidden cards into your hand.
As for when used with Misdirect:
We had to change the card to better match our intent, though we lose the ability to pass cards to each other. It seemed like a fun interaction that we added at the end of our testing, but your scenario wasn’t intended. In this new form, Misdirect would just make someone else hide their own cards that they could later elect (even if immediately after) to take back into their hand. So, in your scenario, if A plays Stash and uses Misdirect, choosing B as the targeter and themselves as the target, all that would happen is that A could play a reaction like Trap or trigger an Action like Curse. Player A would still be the one to hide their cards because they are the target of this new text.
In the future, we may find a new card that can use the mechanic of passing cards, but it ended up causing too many issues that we missed this time.
Thank you for asking this question!