Tridrones were shaped like inverted tetrahedrons and were capable of performing three tasks at a time.
Like all modrons, tridrones 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 tridrone 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.
Like all modrons, tridrones 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.
Tridrones were capable of wielding weapons and were competent combatants, capable of performing three attacks at a time. If destroyed, a tridrone disintegrated completely into dust and a duodrone was instantly upgraded into a tridrone to fill its position. One of the weapons most commonly wielded by them were javelins, which they would hurl at their foes before closing.
Sometime in the late 1480s DR, a tridrone leading a group of monodrones was stranded in the Labyrinth in the Underdark, separated from the other modrons since the previous Great Modron March, over two centuries earlier. After years of wandering, the tridrone managed to keep the group together, but felt responsible for its failure in performing their assigned task.
Tridrones could communicate with other tridrones and with duodrones and quadrones. They were incapable of communicating directly with monodrones and could not comprehend the more advanced pentadrones.
In modron society, tridrones were responsible for leading groups of lesser modrons into battle. They were always created as the result of upgraded duodrones to take the place of destroyed units.
There were about six million tridrones in modron society.
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