Extirpate isn't always card disadvantage you know. Coupled with a a few discard cards and a little luck you can get cards out of their hand. If you're running THoughtseize it's not that crazy to think that you'll have a discard and extirpate when they have 2 cards in hand. It doesn't sound like it would come up often but it's not unthinkable. Just a little more info to add.