I just got all the rare weapons from Eureka as well as Ninjas, Sages, and all the high level spells too. I wanna get all the rare summons before tackling the rest of the game, so can anybody tell me where I can get the ultra powerful summons like Bahamut?

Give me directions by the way. Last time I saved my game I exited the Labyrinth after I got all the stuff in Eureka.