Modrons
Monodrone
Axiomatic Mind. The monodrone can't be compelled to act in a manner contrary to its nature or its instructions.
Disintegration. If the monodrone dies, its body disintegrates into dust, leaving behind its weapons and anything else it was carrying.
Actions
Javelin. Melee or Ranged Weapon Attack: +2 to hit, reach 5 ft. or range 30/120 ft., one target. Hit: 3 (1d6) piercing damage.
Duodrone
Axiomatic Mind. The duodrone can't be compelled to act in a manner contrary to its nature or its instructions.
Disintegration. If the duodrone dies, its body disintegrates into dust, leaving behind its weapons and anything else it was carrying.
Actions
Multiattack. The duodrone makes two fist attacks or two javelin attacks.
Fist. Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit: 2 (1d4) piercing damage.
Javelin. Melee or Ranged Weapon Attack: +3 to hit, reach 5 ft. or range 30/120 ft., one target. Hit: 4 (1d6 + 1) piercing damage.
Tridrone
Axiomatic Mind. The tridrone can't be compelled to act in a manner contrary to its nature or its instructions.
Disintegration. If the tridrone dies, its body disintegrates into dust, leaving behind its weapons and anything else it was carrying.
Actions
Multiattack. The tridrone makes three fist attacks or three javelin attacks.
Fist. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 3 (1d4 + 1) piercing damage.
Javelin. Melee or Ranged Weapon Attack: +3 to hit, reach 5 ft. or range 30/120 ft., one target. Hit: 4 (1d6 + 1) piercing damage.
Quadrone
Axiomatic Mind. The quadrone can't be compelled to act in a manner contrary to its nature or its instructions.
Disintegration. If the quadrone dies, its body disintegrates into dust, leaving behind its weapons and anything else it was carrying.
Actions
Multiattack. The quadrone makes two fist attacks or four shortbow attacks.
Fist. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 3 (1d4 + 1) piercing damage.
Shortbow. Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 80/320 ft., one target. Hit: 5 (1d6 + 2) piercing damage.
Pentadrone
Axiomatic Mind. The pentadrone can't be compelled to act in a manner contrary to its nature or its instructions.
Disintegration. If the pentadrone dies, its body disintegrates into dust, leaving behind its weapons and anything else it was carrying.
Actions
Multiattack. The pentadrone makes five arm attacks.
Arm. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) piercing damage.
Paralysis Gas (Recharge 5-6). The pentadrone exhales a 30-foot cone of gas. Each creature in that area must succeed on a DC 11 Constitution saving throw or be paralyzed for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Modrons are beings of absolute law that adhere to a hive-like hierarchy. They inhabit the plane of Mechanus and tend its eternally revolving gears, their existence a clockwork routine of perfect order.
Absolute Law and Order. Under the direction of their leader, Primus, modrons increase order in the multiverse in accordance with laws beyond the comprehension of·mortal minds. Their own minds are networked in a hierarchical pyramid, in which each modron receives commands from superiors and delegates orders to underlings. A modron carries out commands with total obedience, utmost efficiency, and an absence of morality or ego.
Modrons have no sense of self beyond what is necessary to fulfill their duties. They exist as a unified collective, divided by ranks, yet they always refer to themselves collectively. To a modron, there is no "I", but only "we" or "us."
Absolute Hierarchy. Modrons communicate only with their own rank and the ranks immediately above and below them. Modrons more than one rank away are either too advanced or too simple to understand.
Cogs of the Great Machine. If a modron is destroyed, its remains disintegrate. A replacement from the next lowest rank then transforms in a flash of light, gaining the physical form of its new rank. The promoted modron is replaced by one of its underlings in the same manner, all the way to the lowest levels of the hierarchy. There, a new modron is created by Primus, with a steady stream of monodrones leaving the Great Modron Cathedral on Mechanus as a result.
The Great Modron March. When the gears of Mechanus complete seventeen cycles once every 289 years, Primus sends a vast army of modrons across the Outer Planes, ostensibly on a reconnaissance mission. The march is long and dangerous, and only a small number of modrons returns to Mechanus.
Monodrone¶
A monodrone can perform one simple task at a time and can relay a single message of up to forty-eight words.
Duodrone¶
The blocky duodrones supervise units of monodrones and can perform up to two tasks at a time.
Tridrone¶
Tridrones are shaped like inverted pyramids. They lead lesser modrons in battle.
Quadrone¶
Astute combatants, quadrones serve as artillery and field officers in the regiments of modron armies.
Pentadrone¶
Pentadrones oversee Mechanus's worker populace and can improvise in response to new situations.
Source: Monsters Manual, p. 224