Mark of the Predecessors

You've been bestowed the mark of the predecessors and survived, which enhances your body at the cost of corrupting your mind. Increase one ability score of your choice by 1, to a maximum of 20, to represent this enhancement. Due to the fact that the mark corrupts the user mind and enhances all of it's negative and "Evil" emotions and personas, users of the mark become a lot less empathetic and embrace the darker sides of their personality.

This power also awakens you to the voices of despair, you can hear the suffering witnessed by objects. This aspect of the mark makes it so that your sanity is constantly in trial, you can use a spell slot (It has to be the highest slot you have available at the time) to suppress the voices for a day, you can cancel that suppression at any time, but doing so will require another spell slot to activate it again. While under the influence of the voices the DM can tell you to do sanity checks depending on the story.

The first time you use the mark of the predecessors (upon acquiring it) you receive temporary hit points equal to half your total HP until the end of combat. When the combat ends the character's hp goes to 0 and he is knocked unconscious but alive and all his negative status are reverted (No need for saving throws).

Mark of the Predecessors Abilities. You can use your Mark of the Predecessors to activate the following effects:

Physical Drive. When you make an ability check for STR, CON or DEX, you can roll 1d6 and add number rolled to the check, you also take 2d6 of necrotic damage. You can choose to do so before or after rolling the d20, but before you know whether the check succeeded or failed.

Arcana Drive. When you make an ability check for INT, WIS or CHA, you can roll 1d6 and add the number rolled to the check, you also take 2d6 of necrotic damage. You can choose to do so before or after rolling the d20, but before you know whether the check succeeded or failed.

Whenever you use a mark of the Predecessors ability you roll 1d12 to see if the mark becomes stronger or not, if you roll a 6 or lower the mark evolves and every time the mark doesn't evolve the next roll will be a +2 or lower (meaning if it didn't evolve once, the next time you roll, it will evolve if you roll a 8 or lower and so on).

You can only use one Mark of the predecessor's ability between long rests, that number increases according to the marks level.

Mark of the Predecessors Growth. As the mark grows stronger the character becomes more and more twisted by it's influence, the character becomes more unstable by the level and his sanity is shaken more and more. The mark can go all the way up to level 12 and it receives the following effects at certain levels:

Level 3 - Cursed Appellation. The user becomes cursed by a word and it's cognitive definition. Roll 1d6 to define what "Cursed Appellation" feat you get.

Level 6 - Cursed Form. The influence of the mark becomes physical, the character appearance is affected by it's corruption and becomes almost impossible to hide. You also become capable of using the Mark of the Predecessors ability twice between long rests.

Level 9 - Cursed Mind. The voices of despair become louder and louder, you can no longer use a spell slot to suppress it unless you have the "Mark of the Sinner" feat.

Level 12 - Cursed Trial. The user is warped into a pocket dimension controlled by one of the 7 cardinal demons of sin and is tested. Passing the test grants the player a feat called "Mark of the Sinner", failing the test strips the player of the "Mark of Despair" as well as some kind of "Compensation" taken by the demon himself (whatever it is, it's up to the DM).

THIS IS A HOMEBREW SETTING PLAYTEST MATERIAL FOR "ONITSURI".

The material in this article is presented for playtesting and to spark your imagination. These game mechanics are in draft form, usable in your campaign but not refined by full game development. This material is not officially part of the game. For these reasons, it is not legal in D&D Adventurers League events.
You can find out more about the lore of Onitsuri and it's material in my page.