Arena, Rare, 0-cost
Replace both hands with common attack cards
If not New
Both walls=0
Both towers=35
Ugh, I don't like the conditional effect. With that, this card has the effect of undoing most of the match leading up to its play. Building strong defenses, getting your opponent down to near-nothing, being about to hit a tower victory, finally assembling an ideal hand -- all of these are undone. The only aspects not changed are stock, facilities, and tokens (which will prove temporarily useless with the replaced hand). It's simply not fun to play a heated 80 rounds just to have the game arbitrarily reset itself for a forced, quick finish based entirely on the luck of the draw. And without cost, at that.
I'd prefer, instead of an arbitrary 0 wall 35 tower, if it did a wall reduction, maybe both walls -50, or walls -maxwallheight/2. Or if it didn't make any other changes than to the hands of both players. (I have no issue with the replacement effect by itself.)
Right now, my primary concern is what this would do to a game where someone's facilities have been reduced to 1 or whose stock is under constant attack. Someone slowly managing to build in a drawn out match against a Destruction or Brigand deck, already an insufferable experience, would be twice as frustrated to have this played against him. Simply put, not fun.