Anytime there is a Mordekaiser in the game, I get FPS drops towards the teamfight stage of the game. More Mordekaisers = Worse FPS. This hasn't really been a major problem for me, as there are rarely 2 Mordes in a game (which causes my FPS to drop to around 48), but with OFA re-releasing, just one team of Mordes causes my FPS to drop to around 28, and 2 teams makes the game unplayable.
1. Have a Mordekaiser on screen during mid to late game or a teamfight.
2. Have frames drop.