Sources
CR
Type
Size
Alignment
Movement

Octon Modron

Large Construct, Lawful Neutral

Armor Class 18 (natural armor)
Hit Points 187 (22d10 + 66)
Speed 30 ft., fly 30 ft. (hover), swim 30 ft.
STR
18
+4
DEX
14
+2
CON
17
+3
INT
17
+3
WIS
16
+3
CHA
14
+2
Saving Throws INT +7, WIS +7
Skills Perception +11
Damage Resistances psychic
Senses truesight 120 ft., passive Perception 21
Languages Modron, telepathy 120 ft.
Challenge 11 (7,200 XP)

Traits

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

Combat Ready. The octon has advantage on initiative checks.

Disintegration. If the octon dies, its body disintegrates into dust, leaving behind anything it was carrying.

Spellcasting

Spellcasting. The octon casts one of the following spells, requiring no material components and using Intelligence as the spellcasting ability (spell save DC 15):

At will: detect magic, dispel magic, mending (as an action)

1/day each: plane shift (self only), protection from evil and good

Actions

Multiattack. The octon makes three Tentacle attacks.

Tentacle. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit:14 (3d6 + 4) bludgeoning damage plus 9 (2d8) lightning damage.

Whirlwind of Tentacles (Recharge 5–6). The octon rapidly extends and spins its ring of tentacles. Each creature within 20 feet of the octon must succeed on a DC 16 Strength saving throw or be pulled up to 10 feet in a straight line toward the octon. Then, the octon makes two Tentacle attacks against each creature within 10 feet of itself.

Lore

Constructed on the plane of Mechanus, modrons are partially mechanical beings that belong to a strict hierarchy. Each modron dutifully obeys commands from the rank directly above it and in turn acts as the superior to the rank directly below it, passing down commands from paragons of law to the lowliest monodrone. While most modrons are the lower-ranked base modrons—monodrones, duodrones, tridrones, quadrones, and pentadrones—the upper-tier hierarch modrons hold leadership positions,…