It was possible, however, for a defective quadrone to go rogue and start acting in its own interests or no longer in accordance with its instructions, sometimes even becoming violent. Such rogues were relentlessly hunted by other modrons, although, unlike their properly operating fellows, they could be reasoned with.
On all six sides of their bodies were sensory organs far superior to that of any human. These granted them truesight, in addition to being able to view the infrared and ultraviolet spectrums out to 180 feet (55 meters) and 200 yards (180 meters), respectively. These senses enabled them to rarely be surprised by opponents.
Like all modrons, quadrones were immune to all effects and spells that influenced the mind, fear and attacks that rely on energy from either the Negative or Positive energy planes. They also had a resistance to acid, cold and fire.
Unlike tridones and other lower ranked modrons, these creatures had four complete functions and thus were capable of performing four simultaneous tasks at a time. These functions typically included being able to report actions as well as observations, devise plans, react to situations that were unexpected, and act in accordance to solve those situations.
Quadrones were capable of wielding weapons and were exceptionally proficient with bows, with which they capable of performing four attacks at a time. If destroyed, a quadrone disintegrated completely into dust and a tridrone was instantly upgraded into a quadrone to fill its position.
Quadrones could communicate with other quadrones and with tridrones and pentadrones. They were incapable of communicating directly with lesser modrons and could not comprehend any of the hierarch modrons, such as decatons.
In modron society, they were responsible for supervising other groups of modrons, as well as performing services as multifunctional laborers. During battles they often served the role of a field officer. They were always created as the result of tridrones being upgraded to take the place of destroyed or further upgraded units.
- Halastron, a rogue quadrone adopted by Halaster Blackcloak who lived in the Arcane Chambers level of Undermountain.
- Mike Mearls, Jeremy Crawford, Christopher Perkins (2014-09-30). Monster Manual 5th edition. Edited by Scott Fitzgerald Gray. (Wizards of the Coast), pp. 224, 226. ISBN 978-0786965614.
- Mark Jindra (2001-09-21). The Modrons (Zipped PDF). Web Enhancement for Manual of the Planes 3rd edition. Wizards of the Coast. pp. 8–9. Archived from the original on 2016-11-01. Retrieved on 2018-09-09.
- David "Zeb" Cook (1994). Planescape Campaign Setting, Monstrous Supplement. Edited by David Wise. (TSR, Inc), pp. 16–20. ISBN 978-1560768340.
- Gary Gygax (August 1983). Monster Manual II 1st edition. (TSR, Inc), p. 88. ISBN 0-88038-031-4.
- Gary Gygax (August 1983). Monster Manual II 1st edition. (TSR, Inc), p. 86. ISBN 0-88038-031-4.
- Gary Gygax (August 1983). Monster Manual II 1st edition. (TSR, Inc), p. 87. ISBN 0-88038-031-4.
- Monte Cook, Colin McComb (1997-10-28). The Great Modron March. Edited by Michele Carter. (TSR, Inc.), p. 126. ISBN 0-7869-0648-0.
- Mark Jindra (2001-09-21). The Modrons (Zipped PDF). Web Enhancement for Manual of the Planes 3rd edition. Wizards of the Coast. p. 2. Archived from the original on 2016-11-01. Retrieved on 2018-09-09.
- Christopher Perkins (November 2018). Waterdeep: Dungeon of the Mad Mage. Edited by Jeremy Crawford. (Wizards of the Coast), p. 41. ISBN 978-0-7869-6626-4.