Unsubstantiate
Oracle Text
Return target spell or creature to its owner's hand.
Card Rulings
7/13/2016 Spells that can’t be countered can be returned to their owner’s hand by Unsubstantiate. They won’t resolve.
7/13/2016 A spell that’s a copy ceases to exist as a state-based action after being returned to its owner’s hand. It can’t be cast, and it never counts as a “card” in the player’s hand.
If you have this in your gy.. and a jace vryn flipped.. its a great target to minus on... then proceed to attack and if they cast avacyn you can use it (instant speed) if not, bounce something after combat.
Seems rad in that instance.