He can zone in lane hard. It takes 3 skills to destroy his turrets, and then he just replaces them immediately. If you try to gank him, he sometimes can get a kill even then because of the absurd damage of three turrets. For teamfights, since his turrets do aoe damage they destroy your team, especially the big turret, which takes likes 2-3 smites to kill (way too much health) and if you try to focus heimer he will just zhonyas when he gets low and his turrets and team will continue to kill you. Remove the aoe from his turrets or increase their cd or make him only be able to put 2 turrets or something. It's stupid having the ai do all the work for you.