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

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

Tattoos. Adacher has 3 large tattoos on his body. His pride and joy. The first on his back is a blood fury tattoo which appears as a great, crimson shark demon. On his front he has a Dragon Turtle Tattoo which looks like sea green swirl-like scales and grants him some of the properties of a Ancient Dragon Turtle. The third tattoo covers Adacher's shoulders and arms appearing as black claw marks which glow hot red when activated. This is a Flame Shark Tattoo which melts the ground around him into lava and grants him a 30-foot tremor sense. 

Multiattack. Adacher makes three Punch attacks. It can substitute one with its tail. It can use Hurl Flame in place of any melee attack.

Punch. Melee Weapon Attack: +12 to hit, reach 12 ft., one target. Hit: 15 (2d8 + 6) bludgeoning damage. His attacks also deal an extra 4d6 necrotic damage which heals him. 

Tail. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 10 (1d8 + 6) piercing damage. If the target is a creature other than an undead or a construct, it must succeed on a DC 18 Constitution saving throw or lose 10 (3d6) hit points at the start of each of its turns due to an infernal wound. Each time the devil hits the wounded target with this attack, the damage dealt by the wound increases by 10 (3d6). Any creature can take an action to stanch the wound with a successful DC 12 Wisdom (Medicine) check. The wound also closes if the target receives magical healing.

Hurl Flame. Ranged Spell Attack: +9 to hit, range 150 ft., one target. Hit: 14 (4d6) fire damage. If the target is a flammable object that isn't being worn or carried, it also catches fire.

Steam Breath (Dragon Turtle Tattoo). Adacher exhales scalding steam in a 60-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 52 (15d6) fire damage on a failed save, or half as much damage on a successful one. Being underwater doesn't grant resistance against this damage.

Dragon Turtle Tattoo (1/day). As a bonus action, Adacher activates this tattoo by dragging his hand across his chest causing the swirly jade scales to brighten, flutter, and exhale a thick steam. The air around him becomes heated as Adacher gains 40 temporary hit points and the ability to use Steam Breath as an action. 

Flame Shark Tattoo (1/day). As a bonus action, Adacher activates this tattoo by shaking his wrists which shakes a fiery light into the claw marks. The area heats up even more causing the area within a 10-foot radius to become lava. Any creature that starts its turn or enters the 10-foot radius takes 4d10 fire damage.