The Wizard’s Tower is a nexus of 108 universes which anyone — or anything — can enter as long as they possess the correct World Key. Although it can often seem deserted, its foot-traffic can be measured across the equivalent of millions of standard Earth years. And from that perspective, it has been a rather busy place.
The World Keys
The group of 108 World Keys and their respective TMG1 Mandalas could be considered the primary security system. “Front door” keys, so to speak.
It is possible for anyone to leave the Tower, provided they know how to activate the World Door. However, only those who hold the correct World Key can activate the Tower Door leading back.
The Garage and Catwalks
The Garage has no observable security systems in place outside of the arithmantic symbolons used to operate the World Doors and the Elevator. Attempts in the past to mar the pseudo-stone have failed due to its self-healing ability. The orbs atop the six pillars appear to impervious to both physical and magical probes and attacks.
Many of the rooms carved into the Tower’s wall and accessed from the Catwalks have locked doors. Like the rooms themselves, these locks are conventional, but vary widely from high-tech to magical. These are all easily bypassed by skilled lock-picks and sorcerers.
The Maze of ladders, bridges, and tunnels that exist in the darkness at the top of the Garage is rarely explored, but those who have and live to tell the tale claim traps abound.
The Warehouse and Library
Access to the Warehouse itself beyond the ground-level receiving area is strictly forbidden, and those caught entering are typically killed outright by a swarm of the brass spiders that tend both Warehouse and Library.
It appears that this is the work of the Aurantians. According to an entry in a commonplace book kept by Rodolfo the Clock Maker, the Archivist and Librarian automatons did not limit access to their respective domains when he commenced his research. The automatons would only intercede with a visitor if the visitor attempted to damage or destroy an object.
It appears in a fit of pique over a social slight at an Aurantian party, he arithmantically reprogrammed both automatons to restrict access to anyone other than himself.
The observatory does not appear to have any security tied to it. Like the rest of the Tower, anyone can access the room and (presumably) use the device atop the winding staircase at its center.
There is no lock or chaining device on the alcoves which hold the World Keys. However, the Keys which have been recovered are kept locked in a strange magical device on the floor of the Observatory.
This device was created and brought to the Tower by the Aurantian Parciloquy the Peculiar, and the method of retrieving the Keys within it appears to only be known to Laddys Fermille and himself.