What’s a deck that always catches you off guard?

For me Infernoble, specifically with Mikanko. I don’t see it very often, but when I do ohhhh boyyyy. They always happen to go first, their turn lasts 15 minutes and somehow never time out, and they make the craziest boards I’ve ever seen… and I have no idea what’s going on. I have no idea how to begin breaking it or interact with it, if I have any interaction at all left trying to stop them. What deck is this for you?