Sources
CR
Type
Size
Alignment
Movement

X01

Huge Construct, Lawful Neutral

Armor Class 17 (natural armor)
Hit Points 209 (22d12 + 66)
Speed 40 ft., fly 40 ft. (hover)
STR
19
+4
DEX
16
+3
CON
17
+3
INT
19
+4
WIS
17
+3
CHA
15
+2
Saving Throws INT +9, WIS +8
Skills Perception +13
Damage Resistances lightning, psychic
Condition Immunities Charmed, Frightened
Senses truesight 120 ft., passive Perception 23
Languages all, telepathy 120 ft.
Challenge 13 (10,000 XP)

Traits

Axiomatic Mind. X01 can't be compelled to act in a manner contrary to its nature or its instructions.

Combat Ready. X01 has advantage on initiative rolls.

Disintegration. If X01 dies, its body disintegrates into dust, leaving behind anything it was carrying.

Legendary Resistance (4/Day). If X01 fails a saving throw, it can choose to succeed instead.

Spellcasting

Spellcasting. X01 casts one of the following spells, requiring no material components and using Intelligence as the spellcasting ability (spell save DC 17):

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

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

Actions

Multiattack. X01 makes one Pincer attack and two Tentacle attacks.

Pincer. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit:13 (2d8 + 4) bludgeoning damage plus 10 (3d6) force damage. If the target is a creature, it must succeed on a DC 17 Constitution saving throw or have the incapacitated condition until the end of its next turn.

Tentacle. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit:15 (2d10 + 4) piercing damage, and if the target is a Medium or smaller creature, it has the grappled condition (escape DC 14). Until this grapple ends, X01 can't use this tentacle against other targets. The hexton has six tentacles, each of which can grapple one target.

Reactions

Counter Magic. X01 attempts to interrupt a creature it can see that is casting a spell. If the spell is 3rd level or lower, it fails and has no effect. If the spell is 4th level or higher, the hexton makes an Intelligence check (DC 10 + the spell's level). On a success, the spell fails and has no effect.

Lightning Rebuke. When a creature within 120 feet of X01 damages it, the hexton magically retaliates with an arc of lightning. The creature must make a DC 17 Dexterity saving throw, taking 11 (2d10) lightning damage on a failed save, or half as much damage on a successful one.