batman has killed the justice league a few times and has more than ten green lantern rings and he has the power to do a lot of stuff like man may have a suit made of alien metal and one that turns invisible batman has those too. Iron man has a suit that has the strength of hulk well batman has one that has the strength of superman. Batman was trained by the league of shadows and could wear his invisible suit with his green lantern rings,hack into jarvis blow up all iron mans suits and kill iron man. also if friend calling is allowed then batman could call any member of the justice league such as martian manhunter who if tony called thor manhunter could go into him and kill him no problem or if tony called hulk superman could kill him. So tony stark would lose very fast. An assassin vs some guy who hides behind a metal suit that the assassin would have hacked and destroyed batman wins!