Like all modrons, duodrones had an absolute sense of hierarchy and order, and could not be persuaded to disobey their instructions or betray their purpose in any way.
It was possible, however, for a defective duodrone 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.
If ordered to attack, duodrones would continue fighting until they or their enemy was destroyed. Duodrones were capable of wielding weapons—often halfspears—and were competent combatants, capable of performing two attacks at a time. If destroyed, a duodrone disintegrated completely into dust, and a monodrone was instantly upgraded into a duodrone to fill its position. If victorious, unlike a monodrone, a duodrone could then decide whether or not to pursue additional combatants.
Like all modrons, duodrones 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.
In modron society, duodrones were responsible for supervising units of monodrones. They were always created as the result of upgraded monodrones to take the place of destroyed units. They followed the orders given to them by the tridones. Typically, though they could perform two tasks at once, they were only given one, so that it would have the ability to react to an unforeseen circumstance.
In the modron army, duodrones served as corporals, sergeants, or special shock troops, often leading squads of exactly twelve monodrones.
It was estimated that there were over 55 million modrons in the duodrone caste.
Sometime in the late 1480s DR, a duodrone that was part of a group of modrons that were stranded in the Underdark was held prisoner in the Wormwrithings. The duodrone had been captured by Karazikar, who hoped to learn information about the Maze Engine.
- One of their first miniatures was in the Tomb of Annihilation set in 2017
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