If something comes from a place then that's its provenance, its origin. Like Champagne or a Cornish Pasty. Tau would be a pin too many to allow the rings to turn. The outer ring turns the clutch mechanism that holds the inner ring. It has to turn against the sun, so it needs to go west to east. As you're facing south (ish) that means turning it counter clockwise. A echoey clunk sounds when it turns far enough. Then the inner ring is turned clockwise and woah - the door opens and the adventure begins.

I sort of envisage if either the outer or inner ring are turned the wrong way a trapdoor opens onto a chute that delivers the party to a deeper level of the dungeon complex. Here the monsters are harder to fight because the first couple of levels have useful gear/buffs/spells/whatever that make the subsequent levels easier.

A possible back story for the dungeon could be it's an ancient, long forgotten dwarven city now overrun by some nefarious foes. I haven't thought this far ahead yet though. Perhaps it can be built as a community project or something? The first couple of levels go down to the third level, who then need to fight their way to the throne room where treasures await. Incorrect key rotations dump the party at the third level. The party have to overcome various level bosses and a final boss to get the treasures.