11
Destroy the Evidence
(mtgzone.com)
I wanted to hit a planeswalker and the creature it created, but this notably hits Fable of the Mirror Breaker, Wedding Announcement, Gruff Triplets, and some other non-walkers.
I'm pretty sure this works under the existing rules and you can "remember" a token's creator, but not 100%.
I like that as a fix but for functionality you'd need to make the card an instant or it'd be mostly unplayable because when are you realistically making tokens on your opponent's turn?
Definitely an instant, I didn't notice that it was a sorcery in the original post