Great Old One Redux

Your patron is a mysterious entity whose nature is utterly foreign to the fabric of reality. It might come from the Far Realm, the space beyond reality, or it could be one of the elder gods known only in legends. Its motives are incomprehensible to mortals, and its knowledge so immense and ancient that even the greatest libraries pale in comparison to the vast secrets it holds. The Great Old One might be unaware of your existence or entirely indifferent to you, but the secrets you have learned allow you to draw your magic from it. Entities of this type include Ghaunadar, called That Which Lurks; Tharizdun, the Chained God; Dendar, the Night Serpent; Zargon, the Returner; Great Cthulhu; and other unfathomable beings.

Expanded Spell List

The Great Old One lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

Spell Level	Spells
1st	bane, hideous laughter
2nd	blur detect thoughts
3rd	clairvoyance, sending
4th	black tentacles, phantasmal killer
5th	dominate person, telekinesis

Awoken Mind

Beginning when you first choose this patron at 1st level, your alien knowledge gives you the ability to touch the minds of other creatures. You can telepathically speak to any creature you can see within a number of feet equal to 20 times your Warlock level. You don't need to share a language with the creature for it to understand your telepathic utterances, but the creature must be able to understand at least one language.

Starting at 6th level, you no longer need to see the creature to speak with it using this feature.

Weight of Infinity

Also at 1st level, you can force a creature's mind into confronting the magnitude of the universe and your patron. As an action, you can enter a psychic state, opening your mind and the secrets of the great old one to the mind of a creature you can see within 30 feet of you. For 1 minute or until you choose to end it (no action required), you are deafened and blinded, and all attacks against the chosen creature are made with advantage, as it is scatteredly trying to gather its own mind from wandering away.

You can use this feature once, gaining the ability to use it again when you finish a short or long rest.

Unfathomable Mind

Starting at 6th level, your mind has permanently changed by your patron and magic. Your thoughts can't be read unless you allow it and you gain immunity to psychic damage. If you were to take psychic damage, the creature that attempted to damage you this way takes all the psychic damage you would have taken instead.

Additionally, once per long rest, as an action, you may consume a warlock spell slot. When you do so, for 10 minutes, you gain truesight out of a range of 30 feet.

Entropic Ward

At 10th level, you learn to magically ward yourself against attack by assaulting the mind of your attacker. When a creature makes an attack roll against you, you can use your reaction to impose disadvantage on all attack rolls made against you by that creature until the start of your next turn.

Alternatively, whenever a creature attempts to make you charmed or frightened, you can use your reaction and expend a use of this feature to gain advantage on the saving throw. 

You can use this feature a number of times equal to your proficiency bonus, and you regain these uses when you finish a long rest.

Thrall Genesis

At 14th level, you gain the ability to infect a humanoid's mind with the alien magic of your patron. You can use your action to touch an incapacitated humanoid. That creature is then charmed by you until a Remove Curse spell is cast on it or the charmed condition is removed from it. You can have a number of humanoids charmed equal to half your proficiency bonus (rounded down), and you can communicate telepathically with the charmed creature(s) as long as the two of you are on the same plane of existence.

Additionally, you may expend one of your Mystic Arcanum to cast the Dominate Person spell using the spell level associated with that Mystic Arcanum (ex. You may use your 8th level Mystic Arcanum use for the day to cast Dominate Person at 8th level, however you will be unable to use whatever spell you chose for your 8th level Mystic Arcanum until you complete a long rest).