Bone Golem

Bone Reconstruction. When the Bone Golem takes at least 25 damage in a single turn, it regains 15 hit points at the start of its next turn unless it was hit by radiant damage.

Overwhelming Stench. Creatures that start their turn within 10 feet of the Bone Golem must succeed on a DC 17 Constitution saving throw or be poisoned until the end of their next turn. On a successful save, the creature is immune to this effect for 24 hours.

Magic Resistance. The Bone Golem has advantage on saving throws against spells and other magical effects.

Multiattack. The Bone Golem makes three melee attacks.

Slam. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 21 (3d8 + 6) bludgeoning damage.

Bone Prison. The golem targets one creature it can see within 5 feet of it. The creature encases the target within its ribcage as a prison. The target must make a DC 15 Dexterity saving throw or become restrained. The restrained creature can break free by succeeding on a DC 20 escape check, or by destroying the bone prison (AC 20; 50 hit points; immunity to poison and psychic damage). The golem can only have bone prison active at a time. It may dismiss the bone prison as a bonus action. When the Bone Prison is destroyed, the imprisoned creature takes 20 (4d10) piercing damage as the shattered bones collapse inward.

Bone Shard Volley (Recharge 5–6). The Bone Golem launches a barrage of sharp bone fragments in a 20-foot radius. Each creature in that area must make a DC 17 Dexterity saving throw, taking 27 (6d8) piercing damage on a failed save, or half as much on a successful one.

The Bone Golem can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature’s turn.

• Slam (1 Action). The Bone Golem makes one slam attack.
• Rib Cage Sweep (2 Actions). The Bone Golem sweeps its rib cage in a 10-foot radius. Each creature in the area must make a DC 17 Strength saving throw or be knocked prone and take 14 (2d8 + 6) bludgeoning damage. (cannot be used while Bone Prison is active)
• Bone Reinforcement (3 Actions). The Bone Golem reinforces its body, gaining 20 temporary hit points and making all attacks against it have disadvantage until the start of its next turn.

Mythic Actions (Activated at 0 Hit Points, once per encounter)

When the Bone Golem drops to 0 hit points, it explodes into a swarm of animated bones. It regains 100 hit points and gains the following new traits and actions:

Mythic Traits
Bone Storm Aura. At the start of each of the Bone Golem's turns, each creature within 20 feet of it takes 10 (3d6) piercing damage.

Shattering Screech. When the Bone Golem is reduced to 50 hit points or less, it emits a deafening screech. All creatures within 30 feet must succeed on a DC 17 Constitution saving throw or take 22 (4d10) thunder damage and be stunned until the end of their next turn.

Mythic Actions

• Bone Cage (1 Action). The Bone Golem creates a 15-foot-radius cage of jagged bones around it. The cage has AC 15, 50 hit points, and immunity to poison and psychic damage. Creatures inside the cage take 10 (3d6) piercing damage at the start of their turns.