Axiomatic Mind. The nonaton can't be compelled to act in a manner contrary to its nature or its instructions.

Disintegration. If the nonaton dies, its body disintegrates into dust, leaving behind its weapons and anything else it was carrying.

Modron Inquisition. The nonaton can innately cast detect thoughts and banishment at will, needing no components. Its spellcasting ability is wisdom (save DC 15), and other modrons have disadvantage on their saving throw against it.

Multiattack. The nonaton makes 9 arm attacks.

Arm. Melee Weapon Attack: +8 to hit, reach 10ft., 1 target. Hit: 8 (2d8) slashing damage. 

The nonaton can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The nonaton regains spent legendary actions at the start of its turn.

See. The nonaton makes a perception check.

Swipe.The nonaton makes an arm attack.

Probe (Costs 2 Actions). The nonaton casts detect thoughts.