Mechanus

A few primes think this place is called Nirvana, but where they came up with that barmy notion is anybody’s guess. Mechanus is sometimes called “the Clockwork Universe”, and it’s easy to see how the place came by that name: Mechanus is a world of giant cogs that hover in space at all angles. Teeth interlock, and the cogwheels click and turn to the rhythm of some cosmic harmony – all perfectly fitting for the plane of ultimate, cold law.
Some of the cogs are little, barely more than a small island of matter, while others are hundreds of miles across. Many times, several smaller cogs cluster around one, feeding off its motion. Typically, such knots are a single layer, although each disk may be a realm of its own. Everything is interlocked, and nothing turns unless all of Mechanus’s disks turn.
Petitioners found on this plane are notoriously honest and literal. They don’t interpret instructions or requests, but do exactly what is asked of them. This can be true even if the action leads to death, for petitioners of Mechanus believe they are constantly being tested in their devotion to order and law.