What is "modron"

Modron ("mother") is a figure in Welsh tradition, known as the mother of the hero Mabon ap Modron. Both characters may have derived from earlier divine figures, in her case the Gaulish goddess Matrona. She may have been a prototype for Morgan le Fay from the Arthurian legend.

In the fictional multiverse of the Dungeons & Dragons fantasy role-playing game, Modrons are creatures native to the outer plane of Mechanus. Modrons resemble geometric shapes with humanoid limbs and represent a living, physical manifestation of law without regard to good or evil. They follow a strict hierarchy, with each rank reporting to the rank directly above it, and issuing commands to the ones ranking beneath it. For example, a quadrone modron will report to a pentadrone, and command several tridrones.