Azazel, prince of demons

Transformation. When one is considered a worthy user of the Deathbringer pistols, Azazel can temporarily lend its power to the user. By using an action, you can assume the form of "Azazel, prince of demons" twice a day, for 1 minute. When you do this, your equipped items remain, but you assume all the statistics on this character sheet. Whilst your proficiencies stay the same, any weapons you have been using will also be subjected to changes in statistics. This transformation cannot be undone until the minute has passed.

Exhaustion. Transforming takes a great toll on the user and when it ends, the user is unable to perform any actions or move for 5 (1d6 + 2) rounds of combat. However, every turn during this exhausted state a d20 must be thrown, on a 20 the exhausted state is immediately terminated.

Death. If you reach 0 hit points in this form, you do not revert back into your original form. You perform death saves as usual, but if you roll a natural 1, one of the Death Bringer pistols is destroyed. If you reach 3 failures, you die and your soul is devoured by Death Bringer. If you succeed, you become stable and regain 2d6 hit points. You are unable to take any actions or move during this turn.

Claws Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 15 (1d12 + 3) slashing damage. 

Demise (Recharge 6). As you point to a creature within 60 ft. damned souls of hell start to appear around the creature together with the flames of hell. Each creature in a 20-foot-radius sphere centered on that point must make a DC 16 Dexterity saving throw. A target takes 6d6 fire damage and 6d6 necrotic damage on a failed save, or half as much damage on a successful one. 

Hellish Rebuke. When a creature hits you with a melee attack, you may use your reaction to momentarily surround this creature by hellish flames. The creature must make a DC 16 Dexterity saving throw. It takes 2d10 fire damage on a failed save, or half as much damage on a successful one.