Clockworck Devil

Barbed Hide. At the start of each of its turns, the Clocklworck Devil deals 7(1d12) piercing damage to any creature grappling it.

Devil's Sight. Magical darkness doesn't impede the devil's darkvision.

Mechanically Improved Resistance. The creature has advantage on saving throws against spells and other magical effects due to its fiendish nature but also claims the sturdines of it's metallic frame on the form of resistance against bludgeoning, piercing an slashing damage. 

Shrapnels.  The creature is capable to spend 4 (1d6)  hitpoints on a declared attack to leave pieces of its metalic frame stuck on the enemie's armor. 

At the start of each of its turns, the clockwork devil deals 4 (1d6) slashing damage to the especific creature it applied its shrapnels, as long as within his field of vision, as the metalic fragments cut through the creature's body

Multiattack. The devil makes three melee attacks: one with its horns and two with its claws. Alternatively, it can use Hurl Flame twice.

Claw. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 3) piercing damage.

Horned Attack. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage.

Hurl Flame. Ranged Spell Attack: +5 to hit, range 150 ft., one target. Hit: 10 (3d6) fire damage. If the target is a flammable object that isn't being worn or carried, it also catches fire.