In fact, it was only revealed yesterday, prior to The Lost Caverns of Ixalan streamer event starting
Cyber Dragon, Exiled Force, and Last Will are all wins against a monster-only opening, and there are plenty more that you can find just by analyzing the decklist and some common opening situations
It hits a lot of the early interaction and removal spells, but it doesnt hit the haymakers like Teferi, Hero of Dominaria or Jace, the Mind Sculptor, and is often a poor lategame topdeck
Also from Outlaws of Thunder Junction is the "crime" mechanic, where certain cards have effects when the player commits a crime - that is, if they target opponent, a permanent an opponent controls, or a card in an opponent's graveyard, although it does lead to some very funny statements out of context