Arcane Order
The only things that the party knows about the AO is about their greed and how they seek out items of power. They are all accomplished and generally powerful wizards.
They know Jacoby Drexelhand had connections to them and they overheard Bargle speak about how he was going to give them the airship.
The The Mighty Menagerie have had a few instances where they have come across the machinations of the Arcane Order.