The Beholder

Your patron is a Beholder, an unpredictable and tyrannical aberration. These creatures are immensely prideful always believing themselves to be the greatest, even above their Beholder peers. Paranoia is typical of these creatures, making a contract with such a being quite the endeavor. Nevertheless, they may choose to employ a warlock to serve under them. 

The intent of the subclass is to be played with Intellegence being the casting stat of Warlocks. 

Psionic Talent

You harbor a wellspring of psionic power within yourself, energy that ebbs and flows as you channel it in various ways. This power is represented by your Psionic Talent die, the starting size of which is a d4.

Changing the Die’s Size. If you roll the highest number on your Psionic Talent die, it decreases by one die size after the roll. This represents you burning through your psionic energy. For example, if the die is a d6 and you roll a 6, it becomes a d4. If it’s a d4 and you roll a 4, it becomes unusable until you finish a long rest. Conversely, if you roll a 1 on your Psionic Talent die, it increases by one die size after the roll, up to its starting size. This represents you conserving psionic energy for later use. For example, if you roll a 1 on a d4, the die then becomes a d6. 

Whenever you finish a long rest, your Psionic Talent die resets to its starting size. When you reach certain levels in this class, the starting size of your Psionic Talent die increases: at 3rd level (d6), 5th level (d8), 11th level (d10), and 17th level (d12).

Psi Replenishment. Realign your mind to that of the otherworldly mind which bestows you with intellect and psionic power. As a bonus action, you can calm your mind for a moment and restore your Psionic Talent die to its starting size. You then can’t use Psi Replenishment again until you finish a long rest. Whenever you use this feature, roll your Psionic Talent die against the table below to determine what beholder behavior you're influenced into until you finish a short rest. This roll cannot change your die size. 

1. Nothing Happens.
2. "Although I am perfect as I am, I can strive to be even better."
3. "I am superior to any other".
4. You are very quick to take offense.
5. "I am the center of the universe. If another acts- it is for my sake or a conspiracy against me!"
6. "I pretend to be insane so my enemies underestimate me."
7. "A defeated enemy is a potential minion, I will be looking to use mercy to manipulate."
8. "I sometimes fear that I am a flawed abomination"
9. "My followers are all spying on me, and I seek motivated, powerful allies to destroy them."
10. "I usually ignore reports and advice from my minions."
11. "I often take out my frustration on my minions."
12. "I enjoy taunting rivals with hints of my plans."

Aberrant Mind

When you cast a spell, you can use your mind to form it, rather than relying on words, gestures, and materials. To do so, roll your Psionic Talent die. The spell then requires no verbal component, and if you rolled the level of the spell or higher, the spell doesn’t require somatic or material components either.

While cast this way, this spell looks to be unfamiliar to others even if they have seen the spell used before. 

Psionic Discovery

You can unlock the ability to cast a mind-oriented Warlock spell you don’t already know. After meditating for 10 minutes (which can be done during a rest), roll your Psionic Talent die, and choose a Warlock spell of a level for which you have spell slots and that is in the school of divination or enchantment. You know the chosen spell for a number of hours equal to the number you rolled.

Intelligence Network

You can form a telepathic connection between your mind and the mind of another. As a bonus action, choose one creature you can see, and roll your Psionic Talent die. For a number of hours equal to the number you rolled, you and the chosen creature can speak telepathically with each other while the two of you are within a number of miles of each other equal to the number you rolled. To understand each other, you each must speak mentally in a language the other knows. The telepathic connection ends early if you use this ability to form a connection with a different creature.

Rays of the Eldritch Eye - Invocation

Your eldritch blast is warped by your patron. When you cast your eldritch blast cantrip, you add an additional effect to the spell, determined by the number that you rolled on the damage dice. You can only apply one effect to each creature you hit with eldritch blast. If you hit a creature with multiple beams of your eldritch blast or roll a critical hit with one, you can choose which d10's damage value you want to apply an effect. 

1. Charm Ray. The creature has disadvantage on attack rolls against you until the beginning of your next turn.

2. Paralyzing Ray. The creature has disadvantage on Dexterity checks and saving throws until the beginning of your next turn. 

3. Fear Ray. The first attack the creature makes on its next turn has disadvantage. 

4. Slow Ray. The creature's speed is reduced by 10 feet until the beginning of your next turn.

5. Enervation Ray. The creature can't regain hit points until the beginning of your next turn.

6. Telekinetic Ray. The creature is pushed or pulled 10 feet in the direction of your choice, up to 5 feet up maximum.

7. Sleep Ray. The creature becomes drowsy and sluggish. On their next turn, they can take an action or a bonus action, but not both. 

8. Petrification Ray. The creature cannot take reactions until the end of your next turn. 

9. Disintegration Ray. One nonmagical object that the creature is carrying is destroyed. 

10. Death Ray. The target takes an additional 1d6 necrotic damage

Perceived Threat - Invocation

You may cast the Spiritual Weapon Spell by lowering your Psionic Talent Dice by one level. When cast this way, the weapon deals psychic damage + your Intelligence Modifier equal to your psionic talent die, and the visual form of the weapon always includes eyes all over. 
At 10th level you may bring forth two spiritual weapons within range as your bonus action. On subsequent turns you may use a bonus action to move both, move one and attack with the other, or attack with one and not use the other.

Tyrannical Insight

Starting at the sixth level, you may peer into the mind of another creature by a feat of mental superiority over them. Select one creature you can see within 30 feet of you to be subject to the Detect Thoughts Spell. When casting the spell using this feature, they instead make an Intelligence saving throw and if it's failed they lose d8 INT until they complete a long rest. Until their INT is restored, if it's been reduced to 6 or less they continue to babble whatever memory was drawn out it. Additionally, you gain one of that character's flaws until you finish a short rest or use the Psi Replenishment feature. Your Psionic Talent Die decreases one die size if they fail the save. If they succeed the saving throw, they are immune to this ability for 24 hours. This ability may be used once until you complete a short or long rest. 

Paranoia Justified

Starting at 10th level, the Paranoia of your Beholder Patron has plagued your mind for too long for you to be shocked by anything.

When an enemy moves as a reaction you may roll your Psionic Talent Die. You may move up to that many creatures you can see 30 feet or less in any direction unoccupied spaces you can see. When you take this action, your Psionic Talent die decreases by one die size. 

This ability may be used while surprised. 

Aura of Antimagic

Starting at 14th level, whenever you or a friendly creature within 15 feet make a saving throw against a spell of magical effect, the check is made with advantage.

Additionally, whenever any hostile creature within 15 feet of you makes a constitution check to maintain concentration the check is made with disadvantage.