K, so far I'm planning to set up during the next three or four campaigns the setup of an organization of ex-Agents from Warehouse 12. Their main objective is to recover Warehouse 1, which in my campaign will be Atlantis. In order to protect Warehouse 1 the original Caretaker sunk the gigantic Island, locking it away for all eternity. These artifacts are pre-historic, before 2000 BCE. A lot of the artifacts are simple devices but with amazing powers. The main item of the collection is the Crown of Terra, who ever wields is said to control the entire world, the reason why the warehouse was sunk in the first place.
The Rogue Agents have different agenda's but the main is to uncover the three rings that control Atlantis, When all three are brought together the user can summon atlantis. In this world Atlantis was a floating Warehouse that never was in the same place twice.
I hate doing the cliche of polar opposite bad guys, but I might end up making them all Artifact wielders with a few traits from actual classes. One will definetly be a Intruder/snoop. One might be a faceman. Soldier/veteran. And then to top it off an Ex-Caretaker. The reason why they are looking for Warehouse 1 and know how to get to it, he hasnt told the other Warehouse agents about the Crown.
The Rings are the Ring of the Guardian(Caretaker), King(regent) and the Warrior(agent). The items give boost to certain characteristics but aside from that are unremarkable, unless together.
I might bring the Escher vault into a game. Fun to see knives fall upwards.