The Great Old One.

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.

Level 1 Features:

Cosmic Magic.

When you learn a spell of the appropriate level using your pact magic feature, you also learn the spells on the Cosmic Spells table. The spells count warlock spells for you, and do not count against your spells known.

Awakened Mind.

At 1st level, the pact you made has given you the ability to telepathically communicate with others. As an action, choose one or more creatures you can see, up to a number equal to your proficiency bonus. You and the chosen creatures can telepathically communicate for a number of hours equal to your warlock level as long as they are within 1 mile of you. To understand each other, you must mentally speak the same language.

Psychic Scars.

The pact you made has left you with a mental scar. Roll a d6 to determine the nature of your scar.

Mind Piercer.

You can pierce the minds of others to read their thoughts. You know the Detect Thoughts spell. It counts as warlock spell for you, and it doesn't count against the number of spells you know. You can cast Detect Thoughts without expending a spell slot. You can do so a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Level 6 Feature:

Cosmic Insight.

Starting at 6th level, you begin to receive ancient cosmic lore from your patron. The lore is a muddled mess in your mind but what you can remember allows you to gain the following benefits:
-You have resistance to psychic damage.
-When you cast a spell that deals psychic damage, you can add your Intelligence or Charisma to one damage roll of that spell.

Level 10 Feature:

Eldritch Communion.

Beginning at 10th level, more of the cosmic lore in your mind unravels. Your thoughts can't be read by telepathy or other means unless you allow it. Additionally, you can share the cosmic knowledge you've learned with others, driving them mad. As an action, you force a number of creatures equal to your proficiency bonus that you can see within 30 feet of you, to make a Wisdom saving throw. On a failed save, the creature suffers from your short-term madness for up to 1 minute. Roll on your short-term madness table to determine the nature of the madness. An affected creature can reroll its saving throw at the end of its turns.
Once you use this feature, you cannot use it again until you finish a long rest.

Level 14 Feature:

Truth From Beyond.

At 14th level, you briefly gain an understanding of your patron's cosmic knowledge. As an action, can gain understanding for 1 minute. For the duration you gain the following benefits:
-You gain blindsight up to 60 feet.
-Whenever you make an attack roll, an ability check, or saving throw, you can treat a roll of 9 or lower on the d20 as a 10.
-As a bonus action, you can teleport up to 30 feet to an unoccupied space you can see.
Once you use this feature, you can't use it again until you finish a long rest, unless you spend half of your hit dice to use it again.