They have a tower in Sigil's Lower Ward they renovated after the former occupants... dissapeared. The former occupants were an illithid and a negoi brain/soul/slave traders, so nobody got too upset when they dissapeared. The tower had to be heavily renovated (lots of stone shapes, lots of cleaning) after they took over the place.
Now they're working on a new base of operations in an ancient tower (with an artifact forge) hidden away on the first layer of Pandemonium. Their Sigil tower has a portal to Pandemonium which is close enough to go through and teleport to the tower there, so they'll hold both. The new one will be mostly used for spell research, construct creation, and unspeakable abominations unto nature being produced.
They also have plans to kill two axiomatic illithids who hold a town in Mechanus under sway. They're debating whether to keep the town as their own holding or to let others run it for a fair cut of taxes monthly. This, of course, assumes that they can defeat the pair of axiomatic illithid rulers. But, if they do, they already have enough influence in the town that rulership, should they claim it, won't be difficult.
Hmmm can't think of anything else.