To fight Adam at his most powerful you must banish all other bosses except chanel (once you defeat a boss they will crouch down and you will have a choice to redeem them with LT (DON'T!!). Instead you should continually hit them 'till they vanish. Now you must ONLY redeem chanel with the LT. Once you do this a cutscene will occur and the heart in the midde or the Hub will turn blue. Enter the portal and engage Adam. Good luck and happy hunting.