Hmmm, that feels a bit over the top, but ok. I feel like this particular ability should be ok since it takes so long to activate and allows the opponent to replay everything they initially had since everything not on the battlefield (or exiled) is reshuffled and drawn. Seems like the difference between daze and force of will.
I was just gonna ask how the cards got stacked the library since I was trying to figure out if I could etch a win out of the 2-2 mine and Jacks deck seems to be.
Edit: To clarify though...I totally missed that as well, since all my "testing" only ever made them discard one card...
I think you do better than you had before (you sure do vs me!) so all-win for you!
Some other rulesets define legality of discard by turn (they allow multiple discard in a single turn, but disallow any discard at all before the opponent's second turn). Our ruleset is the "max one" form. And even if it's a not-actually-likely-to-be-used case, the ruleset should be concrete, not negotiable or open to interpretation. Ensures no cases of "You allowed him to run that card? I wouldd have run that card but didn't because I could see it was against the rules!"
But on the academic point of deck stacking resolution: random effects like deck shuffles are chosen to resolve in the best interests of the non-owner of the source of the random effect. Which is to say your opponent gets to stack both decks to the opponent's best outcome. So you get the things you want first last, while your opponent will get the things the opponent wants first first.
Oh, and I believe Scarlet misscored vs Zuty and I copied that misscore. Leyline only makes nonland permanents legendary, so Karakas can't bounce Inkmoth, and Inkmoth wrecks us.
I'm losin' points left and right.