The Heart

Homebrewer's Note: Based off the enemies in the game Darkest Dungeon by Red Hook Studios, so spoilers. Feel free to re-flavor this like a great old one warlock if you just want the features and not the flavor. 14th level feature is OP in comparison to other features like Hurl Through Hell, but I wanted to stay true to the essence of the game, although there are some restriction to make it not blatantly overpowered.

Deep within a bleak dungeon in a decrepit manor lurks a horrifying monster of nerve-wracking power: the very heart of the world, The Heart of Darkness. You have explored the fabled manor, bargained, and been exposed to its power and received its 'gifts'. Now you bear the mark of the manor and are a mere fragment of its horror. Whether or not you use in its name is your choice, but it is forever apart of you no matter what. 

Expanded Spell List

The Heart 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.

Heart Expanded Spells

Spell Level	Spells
1st	hideous laughter, bane
2nd	see invisibility, silence
3rd	bestow curse, blink
4th	confusion, phantasmal killer
5th	geas, modify memory

Additional Cantrip

At 1st level, you learn the vicious mockery cantrip. It counts as warlock cantrip for you, but doesn’t count against your number of cantrips known.

Revelation

"I know better. And I. Will. Show you."

Starting at 1st level, Your knowledge of what lurks beneath the abyss renders you immune to being frightened, and you get advantage on Intelligence saving throws. Additionally, any attempt to read your mind frightens the creature who made the attempt.

Stressful Incantation

"Dazed, reeling, about to break..."

At 6th level, you gain the ability to use a bonus action to empower your spells with maddening force. Next time you cast a spell, choose one creature that you hit or that failed a saving throw against your spell, they must make a Intelligence saving throw against your spell save DC. On success, the target is unaffected. On failure, the target is frightened of you for a minute. The target may use an action to reroll the intelligence saving throw to remove the frightened condition. Additionally, the target goes completely mad for 1 minute and you must roll a d8 to determine which of the effects are received; rerolling and succeeding the intelligence save does not remove this effect.

You can use this feature two times at 6th level, three times at 8th, and four times at 12th. You regain all expended uses on short rest. 

1d8 Statuses	Effects
1-Fearful	The target has lost their nerve and composure. Ranged and spell attacks the target makes has a -4 penalty to attack rolls, and any creature forced to make a saving throw against one of the target's spells has advantage. Additionally, when the target starts their turn within 30 feet of any hostile creature, they must make a Wisdom saving throw. On failure, they are frightened by the closest hostile creature. On success, they are unaffected.
2-Paranoid	The target believes everyone is against them, and they are jumpy. It has advantage on Dexterity saving throws but receives a -4 penalty and disadvantage to all rolls affected by Wisdom. The target cannot willingly move closer to their allies. The target cannot be healed by allies.
3-Selfish	Self-preservation is paramount even at the cost of others. The target cannot use the help action, spells, or features on any allied creatures. If the target has 25 hp or under, they will actively use all their movement to attempt to flee combat. They may roll a DC 15 Charisma saving throw at the start of their turn to resist fleeing. When using a healing spell on themselves, the target has a +5 bonus to hp healed.
4- Masochistic	The target finds solace in pain and seeks its comfort. The target is no longer frightened. The target receives a -4 penalty for AC and rolls affected by Dexterity, and they also have a +2 bonus for any roll affected by Constitution. The target feels the impulse to move toward combat and must move toward the nearest hostile creature using all of their movement. The target may roll a DC 15 Charisma saving throw to resist movement at the start of their turns.
5- Abusive	The target turns their madness into uncontrolled anger and power. They are no longer frightened. They have +2 to attack rolls and +2 to damage rolls. The target must attack the closest creature to it. The target has advantage on attack rolls against creatures not hostile to it. If two creatures are within the same range of the target, the target will prioritize attacking any non-hostile.
6-Hopeless	Despondence has overtaken your target, and all hope is lost for them. The target has disadvantage and a -4 penalty on rolls affected by Charisma. They also have disadvantage on both Dexterity and Strength saving throws. The target has a -4 penalty to melee attack rolls.
7-Irrational	The most evident form of insanity has taken hold. The target is erratic and unpredictable. Any sentence the target speaks is unable to be deciphered for any true meaning. At the start of the target's turns, the DM rolls a d100; on any roll less than or equal to 50, the target must spend its action interacting with the environment or dashing to random locations even if it is harmful. The target has a -4 penalty to any roll affected by Intelligence. The target adds a +3 bonus to their order in initiative until this effect is ended.
8-Virtuous	The target remains stalwart in the face of danger. The target is still frightened and is immune to this feature for 24 hours.

 

Tormentor

"Festering fear consumes the mind!"

Starting at 10th level, You master the exploitation of fear. Creatures you frighten have disadvantage on saving throws imposed by you. Any time you inflict the frightened condition on a creature, the creature takes an additional 3d8 psychic damage. You also have advantage on Intimidation skill checks.

Come Unto Your Maker

"Our creator... and our destroyer."

At 14th level, you call upon your patron to annihilate your foe. Against a creature who is frightened of you, you may use this feature to mark it for death. At the very end of the next round, your patron will instantly kill the creature. This has no effect if the creature has legendary actions. If you are incapacitated before the creature is killed, the attack is cancelled and refunded. Alternatively, you can use this feature to give the frightened condition to a creature. This effect works even if the target is immune to the frightened condition. Creatures with Legendary Actions are not immune to this effect.

This feature is regained upon long rest.