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

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

Commanding. The hexton can innately cast command at will, needing no components. Its spellcasting ability is wisdom (save DC 16), and other modrons have disadvantage on their saving throw against it.

Multiattack. The hexton makes 4 tentacle attacks or 2 greatsword attacks.

Tentacle. Melee Weapon Attack: +9 to hit, reach  5 ft., 1 target. Hit: 25 (4d12 + 1) slashing damage. 

Greatsword. Melee Weapon Attack: +10 to hit, reach 10 ft., 1 target. Hit:  20 (4d10) slashing damage.

Rally. The hexton imbues all modrons within a 15 foot radius with strength. They gain 1d6 temporary hit points.

The hexton 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 hexton regains spent legendary actions at the start of its turn.

Swipe. The hexton makes a tentacle attack.

Rally. The hexton uses the rally action.

Command (Costs 2 Actions). The hexton casts command.