Arcane Leviathan

Gargantuan Construct unaligned

STR	DEX	CON	INT	WIS	CHA
26 (+8)	5 (-3)	21 (+5)	5 (-3)	17 (+3)	8 (-1)

Saving Throws: Str +1, Con +1, Int +2, Wis +8, Cha +4
Skills: perception +3
Damage Immunities: lightning, poison, psychic
Damage Resistances: acid, thunder; nonmagic B/P/S attacks
Condition Immunities: blinded, charmed, deafened, exhaustion, frightened, paralyzed, petrified, poisoned
Senses: truesight 120', passive Perception 13
Languages: understands creator's languages but can't speak

Construct Nature: Doesn't require air food drink or sleep.
Impregnable: If subjected to an effect that allows it to make a save to take only half damage it instead takes no damage if it succeeds on the save and only half damage if it fails.
Siege Monster: Double damage to objects/structures.

Multiattack: One Slam and two Claws or four Lightning Bolts.
Claw: Melee Weapon Attack: +13 to hit, 15 ft., one target, 26 (4d8+8) slashing damage. If target is Huge or smaller it is grappled (escape DC 19). Leviathan has two claws each of which can grapple only one target.
Slam: Melee Weapon Attack: +13 to hit, 5 ft., one target, 18 (4d4+8) bludgeoning damage and target: DC 19 Str save or be knocked prone.
Lightning Bolt: Ranged Spell Attack: +8 to hit 150/600' one target 17 (4d6+3) lightning.
Pylon Discharge (Recharge 5-6): Discharges energy surge at a point it can see within 200' of it. Each creature within 30' of that point: 45 (10d8) lightning and is blinded until the end of its next turn (DC 19 Dex half damage not blinded).

Arcane Barrage: Sends arcane energy toward a creature it can see within 120' of it. Target begins to glow with arcane energy and at end of target's next turn: 35 (10d6) radiant (DC 19 Con half). Damage is divided evenly between target and all creatures within 10 ft. of it except leviathan.