What’s a mortal to make of the modrons — those strange creatures of absolute order that whir and click along in the Clockwork Nirvana of Mechanus? To an outsider, they seem to have no existence other than as a whole. Indeed, there is a saying: “To look at one modron is to look at all of them.”
It is only logical that these creatures are native to Mechanus. Rumor has it that they are the keepers of their mechanical plane, the maintainers of the gears and the polishers of the cogs. Modrons keep the whole place running smoothly and cleanly—without them, Mechanus would surely break down.
- by Mark Jindra, Wizards of the Coast
Modron Supplemental Material : www.wizards.com/dnd/files/modrons.zip