Houserules!
The main houserule I use for warlocks is that they can use their Boon as a spell focus.
Edit: I'll update this with the new options once they're a bit polished. Cloak of Midnight is doing good, just need to polish the invocations. The Bells are less close to ready, but they'll get there.
Also working on a pact boon for making a seeker/arcane archer, and a couple Primal Spirits patrons.
Ok, so these boons are a bit more, thematically, than the normal boons. They are important items with their own stories, and may even be the source of your warlock magic, acting as a patron.
Update:
Cloak Of Midnight
You have uncovered ancient and mysterious artifact known as The Cloak of Midnight. Upon first donning the Cloak, it revealed to you it's nature in a dizzying moment of cosmic clarity, as if the multiverse had been revealed to you from an unimaginable perspective. You can only recall glimpses, but when you came to, the Cloak had become part of you. Permanently.
You can dismiss the Cloak of Midnight, or recall it, as a Bonus Action, or as a Reaction to taking damage.
The Cloak imparts upon you certain benefits.
You can use the Cloak of Midnight as an Arcane Focus
While wearing the Cloak and not wearing armor or using a shield, your AC is equal to 10+Dex+Cha modifier.
As a bonus action, you can reach your hand into the cloak and pull out a melee weapon made of shadows and starlight, called a Night Blade. You are proficient in this weapon. If you let go of the weapon, it fades away after 1 minute. You can dismiss the weapon simply by sheathing it within the cloak. The weapon is considered magical for the purposes of resistances.
If you deal damage with a cantrip while wielding a Night Blade, and the cantrip would do extra damage due to your level, you can forgo that extra damage, and instead make an attack with your Night Blade.
If you find a magical weapon, you can perform a 1 hour ritual to absorb it into the cloak, causing a weapon of the same type which the cloak creates to have the same enchantment. Only one weapon enchantment can be so absorbed. The Cloak of Midnight can also absorb the enchantment from any 1 cloak, necklace, or light armor, in the same manner, and store it. As with the weapon enchantment, it can only hold 1 at a time.
Invocations:
Shadow Shapes: In addition to a weapon, you can pull out other solid object made of shadow from your cloak. They are pure black, have no weight, and are cold to the touch. The object can be any shape you wish but cannot exceed 5' across and 15' long. As long as you are touching it is solid, but fades within 1 minute of you letting go, unless you decide to let it fade immediately. You can also choose to Concentrate, as if on a spell, to keep the shape solid for as long as you can maintain concentration. The shadow shape can be broken with a strength check equal to your casting DC. Creatures have disadvantage on the check if the object is in total darkness. It will also be subject to Concentration checks, and if any check fails, it will fade if subject to direct sunlight (clouds or covering it with your cloak is often sufficient to maintain it), the daylight spell, or similar effect.
Walker In Starlight: While in Dim Light or Darkness, you can use your movement to teleport your speed, so long as your destination is also in Dim Light or Darkness. Like normal movement, this movement can be split up, or used all at once. If you have not moved in this way on your current turn, you can instead use your Action to use this ability, and the destination can be up to 60ft away.
Additionally, any time you are in Dim Light or Darkness while wearing the Cloak of Midnight, you add your Charisma mod to Dexterity checks to Hide, or Acrobatics or Athletics checks.
The Seven Bells of Urit Zohr
The Seven, as they are commonly known, are an ancient magic from a time and place forgotten to all but the most knowledgeable sages. The Kingdom of Skulls. In ancient times, the God King Marwolaeth ruled a large island kingdom, wreathed in mists. Little is known of his origins, or of the woman who defeated him, but her Bells have passed from world to world, hero to hero, always warning their wielder of a terrifying truth.
That which is dead cannot die. Marwolaeth will return.
The Seven compel the undead to accept death, and beings of other planes to return to where they belong.
You gain the following benefits:
The bells are attached to a bandolier, handles stuck out. The bandolier muffles the sound of the bells, preventing accidental usage. You must have a free hand to use the bells, but needn't keep one in your hand. Practice has made you proficient in drawing, using and storing a bell as a single action. You can use the Bells as an Arcane Focus, drawing a bell as part of casting the spell.
When you do so, your spells are more effective against Undead, summoned creatures, and any target that is controlling a summoned or Undead creature.
Summoned or controlled Undead, take extra damage equal to your Charisma Modifier, if the spell deals damage. You can instead choose to cause the individual who summon, or who controls, the target take the extra damage. A creature can only take this damage once per turn.
You are proficient in any ability check made as part of a spell which targets such a creature or effect, such as Dispell Magic or Counterspell.
In addition, you gain mastery of the First Bell, Arharim. You can use the Seven once, and regain the ability after you take a rest. Invocations allow you to master greater bells. Each such invocation also adds 1 to the number of times you can use this feature. You can create up to 7 charms, which protect the wearer against the effects of The Seven. Be warned, however, that no magic can make any creature immune to the Three Greater Bells. Against those bells, the charm only bestows Advantage on saves against the effects.
The First Bell, Arharim
As an action, you draw and ring Arharim, the Bell of Discord first up, in front of your face, and then out and down to your waist, causing a dissonant sound that breaks other's concentration. Each creature within 60' who hears the sound must make a concentration saving throw against your spellcasting DC. If they fail, they lose their concentration on any spell or effect and are deafened until the end of your next turn. Once you use this feature you cannot use it again until you take a short or long rest.
Invocations:
Ull, Malucach, and Rhom
requires: Pact Boon of the Seven Bells of Urit Zhor
You gain Mastery of the Second, Third, and Fourth Bells.
Ull, Bell of Forbiddance
As an action, you draw and ring Ull, Bell of Forbiddance. in a horizontal circle, at your shoulder height. Every creature within 60' of you must make a Con save. If they fail, they take 1d8 damage, and are Frightened until they succeed on a Will save, as an action, to end the effect. If they succeed, they only take the damage. Undead that are being controlled have disadvantage on the saves, and every time they fail a save from this effect, they take damage equal to your Charisma Modifier.
Malucach, Bell of Confusion
As an action, you draw and ring Malucach, Bell of Confusiion, in a tight circle, over your head, pointing up. The bell creates a chime which confuses any creature within 60'. Effected creatures must make a Wisdom save, or be confused. Confused creatures must make another save every turn, at the start of their turn, or they use their action to attack any creature controlling them. If they cannot attack their controller or summoner, or if they are not being controlled and were not summoned, they forget what they were doing, and wander aimlessly until they successfully save. Any creature that is not undead, and is native to the plane they are on, has Advantage on subsequent saves.
Rhom, Bell of Dismissal
As an action, you draw and ring Rhom, Bell of Dismissal, drawing the bell to your waist, then creating a clockwise circle in front of you. Each creature within 60' of you must make a constitution saving throw. If the fail they take 1d10 + your warlock level thunder damage, half as much on a successful save. Creatures reduced to 0 hit points by this effect cannot be turned into undead again. Creatures summoned from another plane, which are reduced to 0hp, return to their home plane, cannot be so summoned again for 1 month.
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Batik and Niada
requires: Seven Bells pact boon, level 5
As your mastery of the bells increases, you learn to better use them to cast your spells, as well.
When you target a summoned or magically controlled creature with any spell which has an attack, or requires the target to make a saving throw, and the attack succeeds or the save fails, you can choose to deal damage to their controller of the being that summoned them equal to your Charisma mod.
Batik, Bell of Destruction
As an action, you draw and ring Batik, Bell of Destruction, in a dramatic vertical slash, across your body with your arm fully extended. A great crash tolls out, and all creatures and objects within 60' must succeed on a Con Save or take 2d10 damage, half damage if they succeed. Undead and beings who are controlling undead creatures have Disadvantage on the save.
Niada, Bell of Naming
As an action, you draw and ring Niada, Bell of Naming, drawing the bell from your shoulder out directly in front of you, as if spashing water on something in front of you. All creatures within 30' of you must make a Wisdom save, or be compelled to answer you one question, asked within the next minute, truthfully. Any creature being summoned or magically controlled that fails it's save will tell you the name of it's master, even if it cannot normally speak. Within the 1 minute, you can ring Niada again, and make a spell attack against each creature that failed it's save. If successful, the master of each creature, if it has one, takes damage equal to your Charisma mod.
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Bannadthur, The Final Bell, Voice of The Last Gate
Requires Seven Bells, level 9
Your mastery of The Seven is complete.
When you use The Seven to cast Dispell Magic, you can choose to use 1 use of your Mastery to target any creature within 20' of you. You learn Dispel Magic and Dispel Evil and Good if you don't know them already. They do not count against your spells known.
You also gain the use of the Final Bell.
As an action, you draw and ring Bannadthur, The Final Bell. Bannadthur requires no special movement, and rings whether you wish or not, upon being freed from it's sleeve. All creatures within 60' are filled with terrible loss of will, and must make a Wisdom save. Your bell charms do not protect fully against this bell, instead only provide Advantage on the Wisdom save. Creatures who fail the save take 2d6 damage and are Paralyzed for 1 hour. On a successful save, creatures are slowed for 10 minutes, and take half damage.
Undead, creatures not of the material plane, and any being who controls, summoned or created such a creature, also takes 2d10 damage and suffers disadvantage on any saves it makes while Paralyzed.
I'll go over it again for format, spelling, etc, but I think it's a good set of invocations and a boon.
