Serpentblood

Your veins run with the blood of creatures such as the Naga and Ankheg, toxic and corrosive.

Corrosive Nature

Starting at level one, your acid slows and weakens your enemies. When you cast a spell of first level or higher that deals acid damage You can use your bonus action to half your targets speed and cause all attacks on them to have advantage. This effect ends when the target is next healed.

Snake's Fury

Starting at 14th level, when you are hit by a melee attack, you can use your reaction to deal poison damage to the attacker. The damage equals your sorcerer level. The attacker must also make a Constitution saving throw against your sorcerer spell save DC. On a failed save, the target is poisoned. They can re-roll their saving throw at the end of their turn.

Serpent Soul

At 18th level, you gain immunity to poison and acid damage.

In addition, whenever you are hit with an attack that deals poison or acid damage you regain a number of hit points equal to the poison or acid damage dealt.

Heart of Poison

At sixth level, you gain resistance to poison and acid damage and immunity to disease. In addition, whenever you start casting a spell of 1st level or higher that deals poison or acid damage, a foul mist engulfs you. This mist causes creatures of your choice within 10 feet of you to take poison or acid damage (choose each time this ability activates) equal to half your sorcerer level.

Poisonous Vigor

At level 6, you are able to bolster your own health at the expense of others. Whenever you start casting a spell of 1st level or higher that deals poison damage, you regain hit points equal to half of the damage dealt.