Gift of Darkness

The flames of hellfire or the curse of undeath runs in your veins.  Some great ancestor of yours mingled with the dark powers, or a storied event that occurred during your lifetime transformed you.  If you draw your power from an ancient union, perhaps that power laid dormant in your bloodline before it manifested itself in you.  Or perhaps you are an ancient and mighty creature yourself, having learned the secret of using your unholy nature to manipulate the threads of the cosmos to produce arcane magic.

Supernatural Senses

From 1st level, your senses are supernaturally heightened, granting you enhanced natural senses and darkvision.  You gain proficiency in the perception skill if you don't already have it, expertise in the perception skill, and darkvision with a range of 120 feet.

When you reach 3rd level in this class, you gain blindsight with a range of 10 feet.

Call of the Night

Starting at 1st level, the wellspring of dark power within you allows you to summon nearby creatures to your aid.  As an action, you can magically reach out to beasts in your area.  1d2 wolves, 1d2 swarms of bats, 1d2 swarms of rats, one swarm of ravens or one swarm of insects answers your call.  Any creatures answering your call must be within 400 feet of you prior to answering and they must be able to physically reach you.  The called creatures arrive in 1d4 rounds.  On your turn, you can mentally command the creatures if they are within 60 feet of you.  The creatures act as allies toward you and follow your commands.  Starting when the creatures arrive, in order to maintain control of them you must maintain concentration as though concentrating on a spell.  After 1 hour or if your concentration ends, the creatures stop following your commands and disperse.

Starting at 3rd level, you can spend 3 sorcery points when the creatures arrive.  If you do so, concentration is not required to maintain control of the creatures, and they remain for 1 hour or until you dismiss them.

Once you have used this feature, you cannot do so again until you have completed a long rest.

Infernal Soul

Starting at 6th level, your soul is destined for damnation.  If you die, your body bursts into flames and your soul is instantly transported to the Nine Hells.  You can be returned to life only by a Wish spell.

Unholy Presence

Starting at 6th level, you can call upon the darkness inherent in you to heal your wounds and destroy holy symbols.  As an action, you can spend 1 or more sorcery points and roll a number of d6s equal to the sorcery points spent.  You regain hit points equal to the total you roll on the dice.  When you do so, each holy symbol of your choice within 15 feet of you bursts into flames until the end of your next turn.  The flames are magic, shedding dim light in a 5-foot radius and burning only the holy symbol.  While a holy symbol is burning in this way, it cannot be used as a focus for casting spells, or to turn undead or fiends.

If you spend 4 or more sorcery points, each nonmagic holy symbol of your choice within range that is not being worn or carried shatters, or bursts into flames for 1 minute (your choice).  Each creature of your choice within range must make a Charisma saving throw.  On a failure, each holy symbol on their person bursts into flames for 1 minute, and you can cast Heat Metal on one metal holy symbol of your choice on their person.  Non-flammable holy symbols that aren't made of metal, and shields and pieces of armor bearing the symbols of deities or religious orders are also valid targets for Heat Metal.  If you cast Heat Metal at lowest level using this feature, you don't expend a spell slot.

Hellish Transformation

At 14th level, you gain the shapechanger creature subtype and you gain the power to transform yourself into a winged fiend.  As an action, you can spend 2 sorcery points to transform.  You can spend 2 additional sorcery points to transform as a bonus action.  Any non-magic gear you are wearing or carrying melds into your fiendish form, and a pair of great bat wings sprout from your shoulder blades.  Your height might also increase by up to 2 feet, and your fiendish form might be hulking and muscular.  While you are in your fiendish form, your creature type changes to fiend and you are subject to the following effects:

• You have a flying speed of 60 feet.
• Your Strength score becomes 20.  If your Strength score is already higher than 20, it does not change.
• Your hands become powerful claws and your maw becomes fearsome and fanged.  Your bite and claws are natural weapons, which you can use to make unarmed strikes.  On a hit, your bite deals piercing damage equal to 2d6 + your Strength modifier, and your claws deal slashing or bludgeoning damage equal to 2d10 + your Strength modifier, instead of the normal bludgeoning damage for an unarmed strike.  When you hit with a bite attack against a Small or larger creature that is not an undead or construct, you regain 1d6 hit points.
• You can attack twice, instead of once, when you take the Attack action on your turn.  You ignore this benefit if you already have a feature, like Extra Attack, that gives you extra attacks.
• You cannot speak intelligibly, other than to cast spells.  You lose concentration on spells, and cannot cast spells that require concentration
• Your skin becomes tough and resilient.  While you aren't wearing armor or wielding a shield, you can calculate your AC as 15 + your Dexterity modifier.

You remain in this form for 1 hour.  It ends early if if you dismiss it as a bonus action.

Regeneration

Beginning at 18th level, the darkness within you grants you unnatural physiology that quickly regenerates from wounds.  You regain 2 hit points at the start of your turn if you have at least 1 hit point and aren't in sunlight or running water.  If you take radiant damage or damage from a silvered weapon, you can't benefit from this feature for 1 minute.  You can't benefit from this feature while you have one or more levels of exhaustion.