race features:
Senses.
Darkvision 60 ft.
Demonic Blood.
You have resistance to fire and poison, but vulnerability to radiant damage.
Fiendish Nature.
You are considered to be both Fiend and Humanoid, and you are considered to have the "Shapechanger" tag. Additionally, you are resistant to fire damage and vulnerable to radiant damage.
Telepathic Bond.
The fiend ignores the range restriction on its telepathy when communicating with a creature it has charmed. The two don't even need to be on the same plane of existence.
Shapechanger.
The fiend can use its action to polymorph into a Small or Medium humanoid, or back into its true form. Without wings, the fiend loses its flying speed. Other than its size and speed, its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.
Actions
Claw (Fiend Form Only).
You deal slashing damage equal to 1d4 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike.
Charm (3 times per Long rest).
You know Charm Person.
You attempt to charm a humanoid you can see within range. It must make a Wisdom saving throw, and does so with advantage if you or your companions are fighting it. If it fails the saving throw, it is charmed by you until the spell ends or until you or your companions do anything harmful to it. The charmed creature regards you as a friendly acquaintance. When the spell ends, the creature knows it was charmed by you.
At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, you can target one additional creature for each slot level above 1st. The creatures must be within 30 feet of each other when you target them.
Draining Kiss (once per long rest).
The fiend kisses a creature charmed by it or a willing creature and can siphon life force from them to heal your wounds. Make a melee spell attack against a creature within your reach. On a hit, the target takes 3d6 psychic damage, and you regain hit points equal to half the amount of psychic damage dealt. Until the spell ends, you can make the attack again on each of your turns as an action.
At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.
Beautiful Corrupters.
A succubus or incubus first appears in ethereal form, passing through walls like a ghost to lurk next to a mortal’s bedside and whisper forbidden pleasures. Sleeping victims are tempted to give in to their darkest desires, indulge in taboos, and feed forbidden appetites. As the fiend fills the victim’s dreams with debauched images, the victim becomes more susceptible to temptation in everyday life.
Inevitably, the fiend enters the mortal realm in tempting form to directly influence a creature’s actions. Appearing in the guise of a humanoid who has previously appeared only in the victim’s dreams, the succubus or incubus seduces or befriends its victim, indulging all its desires so that it performs evil acts of its own free will.
A mortal bequeaths its soul to the fiend not by formal pledge or contract. Instead, when a succubus or incubus has corrupted a creature completely — some say by causing the victim to commit the three betrayals of thought, word, and deed — the victim’s soul belongs to the fiend. The more virtuous the fiend’s prey, the longer the corruption takes, but the more rewarding the downfall. After successfully corrupting a victim, the succubus or incubus kills it, and the tainted soul descends into the Lower Planes.
The succubus or incubus resorts to charming a victim magically only when necessary, usually as a form of self-defense. A charmed creature isn’t responsible for its actions, so forcing it to behave against its will won’t bring the fiend closer to the ultimate prize: the victim’s soul.