School of Nul

Descended from an Atmosian study of the Abyss, the School of Nul has long been considered illegal within Lucidia and many countries beyond, including the entire continent of Sah'Tihr. It studies how energies - or lack-there-of - interact with the physical, tangible reality around us, as well as what the calls from within mean. 

The Abyss - also known as the Void - is a notoriously terrifying dimension, with tears into it leaving those who witness it's horrors mentally mangled for the remainder of their days. Which, coincidentally, seem to come soon after such an interaction. The School of Nul allows for gradual exposure, faint interactions with the beyond that allow the user to adapt to it's horrors and utilize them in the physical plane, and even potentially beyond. It is not without it's difficulties and has been outlawed for a reason, but those who continue their study are no doubt amongst some of the most powerful mages on the world of Daea. For better, or worse. 

Abyssal Seed

You infect an enemy with your Abyssal powers, now sewn into their very being. Unless cured with a Restoration spell, they will take damage equal to your Constitution modifier each turn until it consumes their body and kills them. This can only affect one enemy at a time, and you cannot remove the Seed until the target is dead or cured. 

False Flesh

You enshroud your body with Abyssal energies to cover your wounds; once per round, you can choose to absorb the damage your Abyssal Seed deals as Temporary HP. You cannot absorb more Temporary HP if you still have some remaining by the time the next round starts. 

Bask in the Silence

You silence your mind, and allow the void to consume the parts of you hindered. When you fail a saving throw against a psychological effect, you can spend an action on your turn to retake it as a Constitution Saving Throw, if it wasn't before. 

Abyssal Tear

Your Seed expands in strength, growing throughout your enemy far faster than before. You add a bonus d4 of Psychic damage every time your Abyssal Seed damages an enemy. At the cost of an Exhaustion State, you can increase this to a d10 for as long as the seed is attached to the entity. 

Abyssal Consumption

Every time your Abyssal Seed deals an extra die of damage, that becomes a permanent addition to the total. For example: 
If you dealt 2 + 1d10 damage, and the d10 scored 7, that would be added to your next rolls. It would become 2 + 7 + 1d10, and then that d10 would also be added to future rolls, until the damage caps at your total Constitution Score.