Dragons have four five stages, the youngling stage, the juvenile stage, the adult stage, the ancient stage and the elder stage. But a dragon was not immortal, dragons with longest age were the gold dragon, silver dragon, black dragon and red dragon. So it was not possible for any dragon to reach the elder stage until it has lived seven hundred thousand years three times and it finally sheds its former skin and is reborn young and fresh again. Which meant it was incredibly hard for dragons to reach the or as Bahamut's father intended, impossible.
But everything could be through a back door which there is always a prize for.
The gold dragon stood frozen.
'An elder dragon...a single misstep and everything Lord Rein has worked for until now can go down the drain, no being in this place will be able to match the magical prowes of an elder dragon...I guess I have to let them leave for now'
