If it's the first three bosses of Oberon Monistary...

They're testing us to make sure we are powerful enough to take on Ultima. It wouldn't do for someone weak to stumble over her seal and release her and then have no way to deal with her.


That said, all the bosses we fight in the Ivalice raids are beings empowered by Auracite. Their reasons and desires for being empowered by Auracite are very different though, and that seems to play a part in what type of Lucavi they transform into and what the goals of those Lucavi are.