> APPRENTICE: examine mysterious round marking on floor

Ah yes, this round marking on the floor, a worn out imprint on the ground. Suspiciously round. About the same size as the HEAVY, STONE DISK the APPRENTICE just tried tossing.

The HEAVY, STONE DISK, also known as the TELEPORTATION PAD.

That's where the TELEPORTATION PAD goes.

Yeah see? It's activated now. It's currently the APPRENTICE's only safe exit, its synced with the bottom floor of the tower.

Maybe it could have been a bit more clear that this is where it goes, but moving it off it's spot is the closest thing the APPRENTICE has to "locking their door."