The Possessed

Eldritch Gift

At 3rd level, you are possessed by a foreign being, or such a being already within you gives you control over a portion of its power, granting you an eldritch invocation of your choice. When you reach 7th, 12th and 18th levels, you gain additional invocations of your choice. When you gain a level in this class, you can choose one of the invocations you know and replace it with another invocation that you could learn at that level.

This does not come from a patron, and does not grant any boon. The level prerequisite for any Invocation is doubled, but uses your fighter level instead of your warlock level. Invocations that allow you to cast a spell using a warlock spell slot can be cast once per day without using a spell slot, and Charisma is your spellcasting stat for all spells you gain from eldritch invocations.

Spirit Power

You gain proficiency in your choice of Arcana, History, Nature, or Religion, and 2 warlock cantrips of your choice. Charisma is your spellcasting stat for these cantrips.

Striking Specter

Starting at 7th level, you get a special reaction that you can take once per round turn. When you would be able to make an attack of opportunity, you can instead use this special reaction to have your possessor lash out at the creature, dealing 1d6 + your Charisma modifier damage on a hit. If that creature damaged you since the start of your last turn, your possessor has advantage on the attack.

Incorporeal Possessor

Starting at 10th level, your possessor can shield you from an attack, reducing the damage to zero and healing you for 1d6 hit points. You cannot use this feature while unconscious.

Once you use this feature, you can't use it again until you finish a long rest.

Seeing Spector

Starting from 15th level, your possessor can reach out and sense around you, warning you of things you may have missed. You have advantage on Insight (Wisdom) and investigation (Intelligence) checks.

Infused Foresight

Starting at 18th level, you can cast Foresight requiring no material components, targeting yourself, as an action. The effect lasts for 1 hour. You can use this ability once per long rest.