Those few who were brave or mad enough to delve into the lost knowledge and lore of the inhuman civilizations of eons past almost always find themselves forever changed. Perhaps they came upon these secrets by chance, or perhaps they sought them out. Regardless, one thing is certain: they command dark and terrible magics best left buried and are capable of commanding otherworldly beasts and abominations. These sorcerers are often cruel, hubristic and villainous. This is not to say all are, however. Using many of these powers comes at great cost to the one invoking them for corruption begins to taint their mind, body and soul.

Eldritch Corruption

Each time you use a class ability, you take an associated amount of corruption points. The effects of corruption points stack and each time you successfully take a long rest, lose 1 point of corruption. If Lesser Restoration or Remove Curse is cast on you, lose 1 point of corruption and if Greater Restoration is cast on you, lose 2. The effects are as follows:

1-5: Your physical appearance begins to change. You gain advantage on intimidation checks.

6-10: The corruption seeping through you has empowered your attacks and spells. All of your spell damage and attacks now do an additional 1d8 necrotic damage. This amount increases by 1d8 at level 5, 2d8 at level 10, 3d8 at level 15 and 4d8 at level 18. However, your body has also begun to wither. You gain disadvantage on all strength and athletics rolls.

11-15: The corruption has shielded your mind from outside influence. You are now immune to fear and being charmed. However, your mind has begun to fracture. Whenever you attempt to use a class ability, make a wisdom save equal to your spell save DC. On a failed roll, you go temporarily mad and become incapacitated until the beginning of your next turn.

16-19: You are becoming something more. Any creature that makes an attack roll against you does so at disadvantage. However, your soul has become corrupted to the core and has begun to unravel. Each time you make an attack roll, you take 1d4 psychic damage. All successful attacks against you also deal an additional 1d4 psychic damage.

20: Roll a d4. On each of the following results, something occurs

1-This character dies and cannot be revived with Back from the Void.

2-This character explodes and is killed in a corrupted magical blast. All creatures within 30 feet of you must make a dexterity save equal to your spell save DC. On a failed save, they take 8d6 force damage and on a successful save, they take half damage.

3-This character is set upon by otherworldly beings and pulled into another plane of existence.

4-This character is permanently transformed into a Gibbering Mouther. For its stats, see the Monster Manual. Control of the player character is turned over to the DM. 

 

Voices of the Dead

 

Starting at 1st level, once per long rest, you can choose to commune with the spirits of the deceased to gain otherworldly information. The spirits can answer any question you might have, at the discretion of the DM. They are only able to answer one question per use. Each time you use this ability, you take 1 point of eldritch corruption.

Dark Calling

Starting at 6th level, once per long rest, you can call and bind a Flying Horror to your service. This monster can be mounted and flown on and gets its own initiative role in combat. This counts as a concentration spell and any time you lose concentration or use another ability that requires concentration, the Flying Horror is immediately dismissed and you take 6d6 psychic damage and 1 point of eldritch corruption. You can choose to dismiss this creature using an action and take no damage. The Flying Horror remains bound to you until you either lose concentration or choose to dismiss it. Each time you use this ability, you take 2 points of eldritch corruption.

Back from the Void

Starting at 14th level, you can choose to use an action to bring yourself back to life if you are dead and your body is intact. You return to life with 1 hit point. Each time you use this feature, you take 10 points of eldritch corruption.

Dark Summoning

Beginning at 18th level, once per long rest, you can choose to summon a Babau to your service using an action. This creature gets its own initiative roll in combat and this ability counts as a concentration spell. The Babau remains with you until you choose to dismiss it or you lose concentration. If you lose concentration or use another ability that requires concentration, the Babau is immediately dismissed and you take 10d6 psychic damage as well as 2 points of eldritch corruption. You can choose to dismiss the creature with an action and take no damage. Each time you use this feature, take 5 points of eldritch corruption.