Bonerender Mutator

Mutations: The Mutator has the ability to reshape their own body into a living weapon.  Unless otherwise stated the activation of a Mutation takes one action. If relevant, the DC of a Mutation effect is 17. Unless specified, when a mutation is active a Mutator is obviously a disfigured and aberrant creature, provoking hostility in all creatures around it and taking disadvantage on all Charisma saves and all Charisma rolls except Intimidate, where it receives advantage. Any and all active mutations may be dismissed as a free action, and require a Bonus Action to active unless otherwise stated. 

Unarmored Movement: The Mutator can move across vertical surfaces or liquids on their turn without falling during the move. It must end its movement on a olid surface that can support its weight, but can hang from vertical surfaces.

Inhuman Reflexes: The Mutator can make up to two Reactions per turn.

Consume Biomass: The Mutator's infection is driven by the need to spread and grow, which translates to its host in unpredictable ways. When within 5 ft of a creature that is killed or drops to 0 hit points, the Mutator must make a DC 15 Wisdom saving throw or be driven by hunger to consume the creature as a reaction. Consuming the easily accessible flesh of the creature restores one hit die to the Mutator's total hit dice and provides the opportunity for the Mutator to expend hit dice as if they had just completed a short rest. This effect is not triggered by a construct, undead, or interplanar being's death, and a creature that has been dead for more than one round does not trigger this ability.

Multiattack. The Mutator may make three attacks on its turn; two claw attacks and a bite attack.

Claw. Melee Weapon Attack: +8 to hit, reach 10 ft., single target. Hit: 14 (2d10 + 4) slashing damage and 4 (1d8) poison damage. 

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., single target. Hit: 8 (1d8+3) piercing damage + 13 (3d8) acid damage.

Retractable Spines. Deal 1d8 piercing damage to any creature that attacks it with a natural weapon or successfully grapples it.

Boneshield: When the Mutator takes damage it may increase its AC by 5 until its next turn. This does not cancel the damage from the initial hit, but may prevent later attacks from landing. While this is in effect, it has disadvantage on Dexterity saving throws.