Rusko
Rusko has been an absolute nightmare on the historic brawl queue for several months now. I think I play against him legitimately more than 75% of the time and the play patterns that decks creates are obnoxious. I get that some commanders get overplayed when they released or the match making doesn't know where to put them power wise immediately, but Rusko came out several releases ago and remains ubiquitous to the point of nausea. Either the card needs to get an adjustment (it is an Alchemy card after all) or match making for it needs a major adjustment. The card just interacts very very poorly with the format. Historic Brawl is basically the only format I have played recently and his presence just makes me want to quit playing Magic altogether.