Magic Weapons. The Juggernaut's weapon attacks are magical.

Immutable Form. The Juggernaut is immune to any spell or effect that would alter its form.

Siege Machine. The Juggernaut deals double damage to objects and structures.

Bulwark Stance. The Juggernaut has advantage on any ability check or saving throw it makes to avoid being pushed, pulled, or knocked prone.

Adamantine Plates. Any critical hit against the Juggernaut becomes a normal hit.

Damage Threshold. Any time the Juggernaut takes damage that is less than 12, it takes no damage instead.

Innate Spellcasting. The Juggernaut's innate spellcasting ability is Intelligence (spell save DC 16, +8 to hit with spell attacks). The Juggernaut can innately cast the following spells, requiring no material components:

2/day each: Absorb Elements

1/day each: Destructive Wave

Multiattack. The Juggernaut makes two attacks, either can be a Thunder Fist or Shockwave.

Thunder Fist. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 5) bludgeoning damage plus 5 (1d8) thunder damage.

Shockwave. The Juggernaut slams it's fist down at a point within 10 feet of it. All creatures within 10 feet of the point must make a DC 18 Strength saving throw or take 16 (4d6) thunder damage and be knocked prone. On a successful save creatures take half as much damage and are not knocked prone.

Adamantine Charge. The Juggernaut moves equal to it's speed in a straight line, this movement does not provoke opportunity attacks. If the Juggernaut moves through a space occupied by another creature that is Large or smaller, that creature must make a DC 18 Dexterity saving throw or take 23 (3d10 + 5) bludgeoning damage and be knocked prone. On a successful save the creature takes no damage, is not knocked prone, and is pushed 5 feet out of the Juggernaut's space into an unoccupied space of the creature's choice. Objects and structures that take damage during this charge take triple damage instead of double damage.