Youthful Vengeance

When the enemy youths had entered the final trial area, no one had figured out how they had done so. John assumed they most likely had a way out of it, but once they entered the temple realm, there was no leaving it. 

While he didn't know of the teleportation formation or the fact that it was destroyed, he correctly assumed that the enemy youths only entered the final temple realm because they had no other choice. 

'If their means of escape was located where they entered the realm, they would have never entered the final temple. Since they did, it means that either this was their planned way of leaving the realm, or something went wrong with their original plan.