2020-08-07 : If the target player for Jace's last ability has no cards in hand, that player shuffles nothing into their library, and that player's library will remain empty. That player won't lose the game until they try to draw from the empty library.

2020-08-07 : You draw three cards and put two cards back all while Jace's second ability is resolving. Nothing can happen between the two, and no player may choose to take actions.