Thanks for that! I was going to talk about siege provisions moving through the portals Teleportation Circle, so good to know it’s restricted on that.
Re. exploits from enemies, my idea is that there are 32 “Teleportation Circle Traps” that are isolated corridors with two permanent circles at either end, an “external” circle that is to be connected to the external environment and an “internal” circle that is connected to the Mustering Hall itself. So you have your highly disciplined troops moving at a precise jog go through an external->trap temp circle in 1 round before it closes and then mages in the Mustering Hall open another internal->trap temp circle. The thought is that if bad guys get into one of these traps, they still don’t have immediate access to the citadel. (If I can figure out a good encounter for the players, I might trap them in one of these and throw in a “can be flooded” vs. maintenance tunnels or air shaftts, maybe a passage above with murder holes, etc. But if I can’t do something with it, it’s just going to be dungeon-dressing and its okay if it’s not 100% logical.)