Brago, King Eternal Near the best of the best, we have Brago, King Eternal
With enough mana you can poison someone for 4, and even protect it via regenerate
Oh, and if you still arent convinced by its power, lets just say that this card is banned in Legacy for a reason
Things were looking dire in that game until used Kuldotha Forgemaster to cheat a Myr Incubator onto the field, and a turn later I used it to exile 24 artifacts from my library, cheat 24 Myr onto the field with some dude that would push damage out when artifacts entered, and that was game
Yarok's decks include lots of creatures and other permanents with powerful ETB effects, such as Acidid Slime or Mulldrifter
If theyre hellbent at the start of the turn, you basically make them skip the draw step, unless they drew an instant