Harrowing Event: Your family has a history of practicing the dark arts. You dabbled once and felt something horrible clutch at your soul, whereupon you fled in terror.

Heart of Darkness: Those who look into your eyes can see that you have faced unimaginable horror and that you are no stranger to darkness. Though they might fear you, commoners will extend you every courtesy and do their utmost to help you. Unless you have shown yourself to be a danger to them, they will even take up arms to fight alongside you, should you find yourself facing an enemy alone.

Shadow Sorcerer Quirks: You are always icy cold to the touch, You barely bleed, even when badly injured.
Eyes of the Dark: You have darkvision with a range of 120 feet.

Strength of the Grave: Starting at 1st level, your existence in a twilight state between life and death makes you difficult to defeat. When damage reduces you to 0 hit points, you can make a Charisma saving throw (DC 5 + the damage taken). On a success, you instead drop to 1 hit point. You can't use this feature if you are reduced to 0 hit points by radiant damage or by a critical hit.
After the saving throw succeeds, you can't use this feature again until you finish a long rest.

Font of Magic
Metamagic: Twinned Spell, Quickened Spell

Tentacle of the Deep:At 1st level, you can magically summon a spectral tentacle that strikes at your foes. As a bonus action, you create a 10-foot-long tentacle at a point you can see within 60 feet of you. The tentacle lasts for 1 minute or until you use this feature to create another tentacle.

When you create the tentacle, you can make a melee spell attack against one creature within 10 feet of it. On a hit, the target takes 1d8 cold damage, and its speed is reduced by 10 feet until the start of your next turn. When you reach 10th level in this class, the damage increases to 2d8.

Gift of the Sea:Also at 1st level, you gain a swimming speed of 40 feet, and you can breathe underwater.
As a bonus action on your turn, you can move the tentacle up to 30 feet and repeat the attack .
You can summon the tentacle a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.
Rod of Retribution: This adamantine rod is tipped with a glowing crystalline eye. The rod has 3 charges and regains all its expended charges daily at dawn.
When a creature you can see within 60 feet of you damages you while you are holding this rod, you can use your reaction to expend 1 of the rod's charges to force the creature to make a DC 13 Dexterity saving throw. The creature takes 2d10 lightning damage on a failed save, or half as much damage on a successful one.