Quote Originally Posted by KizuyaKatogami View Post
I would believe this if they didnt explicitly state the tower functions as his power source basically. Hence why once he gets a certain distance from it he begins to weaken. He basically starts running out of energy and it drains him. He really shouldnt have had any left after being that far down there for however long he was.
How much of it was a lie though? Remember, on Mt. Gulg he was about to throw himself and the Lightwardens power into the Rift, something that shouldn't have been possible if he was indeed weakened that much. He may have been purposefully holding onto a specific amount of power for that purpose and doing everything he could to avoid using it. Not to mention that Emet-Selch wanted him alive so he could discover how he traveled through the Rift and time, so Emet-Selch may have also been providing him with aether to keep him alive while in The Tempest.