For those who are not aware of the lore, the Agrius was the Garlean's flagship vessel when the initially attempted to invade Eorzea, along with a fleet of numerous other airships which were locked in combat with a swarm of Dragons that filled the sky. The eventual culmination of the battle ended when an enormous god-like Dragon known as Midgardsormr came down from the sky and destroyed the Agrius, killing himself in the process.

This all takes place 10 years before the events of 1.X and 15 years before current events, though the wreckage of the airship as well as the corpse of the great wyrm still remain at the center of Silvertears Lake (now known as Mor Dhona). Speculation based on the original trailer is that this battle was also the cause of the Primals coming into existence (or being released) as well as the aether imbalance in Eorzea, so with this in mind what kind of strange creatures might still be lurking in the wreckage of the old ship, or in the depths below where the Primals may have been released from?

It all seems like there is just too much here for them not to do something with and I would love to see a dungeon come from this area one day. For whatever reason my mind immediately goes to Anima from FFX lurking as the boss(s) of the dungeon, first needed to climb to the top of the wreckage where you find its upper half then you need to dive to the bottom where you fight its lower half.