Plagueborn

Plagueborn are people born from or changed by disease in some way. Some may come from long lines of medical practitioners, destined to be the opposite of their heritage, while some may be the sole survivors of village-wide sicknesses. No matter how they came to be a Plagueborn, they are now destined to spread illness and disease wherever they may go. Many have minor deformations that get worse as they become more powerful. These deformations can range from hard skin resembling boils to permanent rashes but come in many forms. 

Walk Amongst Filth

Your body is used to the horrors of disease and the rot it can bring upon you. At 1st level, you gain resistance to poison and necrotic damage. Additionally, you have advantage against being poisoned and contracting disease.

Deathly Affinity

Your body morphs and corrupts the spells you cast. Beginning at 1st level, when you cast a spell of 1st level or higher that deals acid, cold, fire, lightning, or thunder damage, you may instead change its damage type to poison or necrotic. You may use this feature a number of times equal to your charisma modifier, regaining all uses on a long rest.

Potent Dosage

Starting at 6th level, when you cast a spell that deals poison or necrotic damage, you may shift them to become more potent. You may spend sorcery points in the following ways:

-Deal an extra 1d4 of the damage type for every 1 sorcery point spent, up to your Charisma modifier.

-Spend sorcery points equal to the spells level to ignore resistance. Cantrips cost 1 sorcery point.

This feature may be used in combination with Deathly Affinity.

Senses of The Sickly

At 14th level, you are always under the effects of a Detect Poison and Disease spell. You can also use an action to cause a number of creatures equal to your Charisma modifier to make Wisdom saving throws against your spell save DC. On a failure, they take 4D12 necrotic damage and they become frightened of you. On a success, they take half damage and are not frightened.

Rotting Formation

Beginning at 18th level, you can channel the very essence of disease and filth. As an action, you may transform into a horrid, rotting form of yourself, gaining the following benefits for 1 minute:
-Immunity to poison and necrotic damage, as well as the poisoned condition.

-When you deal necrotic or poison damage, you deal bonus damage equal to your charisma modifier + your proficiency bonus.

-Hostile creatures within 30ft of you at the start of your transformation must succeed a Constitution saving throw or be poisoned for 1 minute.

-Friendly creatures within 30ft of you gain resistance to poison and necrotic damage, as well as advantage against being poisoned

You may use this transformation only once before taking a long rest.