Chernabog

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.

Wing Sweep. If a player is under 20HP, the devil can knock them prone any time the player is within 15 feet of the flying devil.

Multiattack. The devil makes three melee attacks: two with its fork and one with its tail. It can use Hurl Flame, slash, or slam attack in place of any melee attack.

Fork. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 15 (2d8 + 6) piercing damage.

Tail. Melee Weapon Attack: +10 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 17 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: +7 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.

Finger of Death (Recharge 5-6, 7th Level Spell). Chernabog's signature move. He extends his finger toward a creature it can see within 60 feet and the creature is engulfed in a sickly red light. The target must succeed on a DC 14 Constitution saving throw or take 62 (7d8 + 30) necrotic damage, or half as much on a success. A creature killed by this damage rises at the beginning of the lich's next turn as a zombie under the lich's control.

Slash attack

Slash attacks from claws are melee attacks that do slashing damage on a hit.

Bloody Rampage. When Chernabog takes damage, it makes one Slash attack against a random creature within its reach, other than its master.

Shadow Walk: Chernabog teleports 60 feet to a location it can see.

Ascension: Chernabog is able to fly up to 30 feet in the air. 

Bind Faith. One humanoid creature that died in the last 20 minutes rises as a Demon (30HP) under Chernabog's control that acts on his initiative. 

Demonic Hunger. (3/Day) Chernabog can feast on souls around him and gain resistance to all damage and advantage on attack rolls until the end of its next turn. If Chernabog feasts on a physical corpse and not a soul, it can use an extra bonus action.

Rotten Foot (2/Day). As a reaction to a creature falling prone within 10 ft of it, Chernabog can kick them into the ground around the creature . Its foot can be attacked (AC 17; 20 hit points; immunity to psychic damage). 

Catching a Thrown Weapon. Catching an object thrown as part of a thrown weapon attack
is more difficult. The DC is 10 + the attacker's thrown
weapon attack bonus for any thrown object or 15 + the
attacker's thrown weapon attack bonus if the object has the
thrown weapon property. Alternatively, the DC is 15 for any
thrown object or 20 if the object has the thrown property.
On a failed check, the catcher is automatically hit by the
attack, and a 1-5 on the check causes the attack to
become a critical hit.

Wing Slash. As a reaction to a creature entering its wings reach, Chernabog swipes his wing and forces the creature to succeed on a DC 14 Strength saving throw or be pushed 10 feet away. A creature that fails this save by 5 or more is additionally knocked prone.

Song of the Dead. As a reaction to a creature leaving its reach, Chernabog lets out a wretched shriek. Each creature within 60 ft. that can hear it must succeed on a DC 15 Wisdom saving throw or be unable to move away from Chernabog until the beginning of his next turn.

Firey Retribution. In response to dropping to 15 hit points or fewer, Charnabog engulfs into black flames. All other creatures within 30 feet of it must each make a DC DC 17 Dexterity saving throw, taking 9 (2d8) fire damage plus 9 (2d8) thunder damage on a failed save, or half as much damage on a successful one.

Demon Metamorphosis (1/Day, 9th Level Spell). As a reaction to being reduced below 50 hit points, Chernabog forces one creature it can see within 40 feet to make a DC 17 Constitution saving throw. On a failed save, the creature's flesh begins to roll in upon itself as the creature's body slowly turns itself into a demon, gaining vulnerability to all damage and disadvantage on all attacks and saving throws. An affected creature makes a DC 17 Charisma saving throw at the end of each of its turns, ending the effect after three successes, or transforming into a Horned Devil under the DM's control after three failures until cured by a Wish spell or similar magic.

Rotting Regurgitation. A massive tide of corpses spews from Chernabog's mouth in a 30 foot cone. The area becomes difficult terrain, and each creature in the area must succeed on a DC 19 Strength saving throw or take 32 (5d8) bludgeoning damage and be knocked prone, or take half as much damage on a success.

Claw Flick. Melee Attack: +6 to hit, reach 5 ft., one target. Hit: 20 bludgeoning plus 3 necrotic damage and the target must succeed on a DC 14 Strength saving throw or be thrown 10 feet back and be knocked prone.