Siegecrafter and thok are what seems to give people the most problems on the flex/normals I've run too. If people are going to get stuck on something, it's those movement intensive fights. It's amazing how people can do something hundreds of times and still not know to anticipate fixate/crawler mines.Pretty sure most LFR wipes I've witnessed were on Siegecrafter. Garrosh a couple of times, the Galakras event a couple of times. But yeah, Siegecrafter is the worst for LFR.