Enigma: At 1st level, once per short rest, you can use your action to bestow or receive a sphinx’s riddle.

Receive Riddle: You gain a vague divination of the future, present, or past in the form of a riddle from your patron. Your DM can make up a riddle for you or you can make an INT check to solve it. The DC depends on how difficult the DM determines the riddle to be or the importance of the divination. If you fail at this check, the riddle remains unsolved.

Bestow Riddle: You confound a creature with a riddle from the sphinx that they must answer. You can only target a creature with INT greater than 3 that can understand a language you can speak. The creature has disadvantage on attack rolls, saving throws, and ability checks that don’t use INT until they solve the riddle. The creature can attempt an INT save at the start of each of their turns against your spell save DC, solving the riddle on a success and ending the effect.

Abrade: You wear away at an object or creature as if by many years of sandstorms. You can use your action to deal 1d6 slashing damage for every two warlock levels you have (max 10d6) to a creature or object no larger than Large. A creature or attended object can make a CON saving throw to resist this effect, taking half damage on a successful save. Objects take double damage from this ability. Wooden objects are usually destroyed and metal objects often become weaker and more blunt or smooth. Once you use this ability you cannot use it again until you finish a short or long rest.

Inscrutable: At 10th level, you can detect if creatures are knowingly lying in your presence. You also can automatically attempt saving throws against illusions without needing to interact with them first.

(Androsphinx) Roar of the Sphinx: At 14th level, if your patron is an Androsphinx, you can use a warlock spell slot up to three times a day to emit a magical roar in a 60 ft. cone emanating from your mouth. Each time you roar before finishing a long rest, the roar is louder and the effect is different, as detailed below. Each creature within the roar’s area must make a saving throw against your spell save DC.

First Roar: Each creature that fails a WIS saving throw is frightened for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Second Roar: Each creature that fails a WIS saving throw is deafened and frightened for 1 minute. A frightened creature is paralyzed and can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Third Roar: Each creature makes a CON saving throw. On a failed save, a creature takes 8d10 thunder damage and is knocked prone. On a successful save, the creature takes half as much damage and isn't knocked prone

(Gynosphinx) Ultimatum: At 14th level, if your patron is a Gynosphinx, you can use your action once per day to ask a deadly riddle of a creature that can understand you. The creature must attempt to answer the riddle each round with an INT saving throw against your spell save DC. After three failed saves, the creature is affected as if by a Disintegrate spell, taking 10d6+40 force damage and turning to dust if they die from the damage.

Invocations:

Mirage of the Sphinx: (Prereq: 7th level, Sphinx Patron) You can cast Hallucinatory Terrain as an action (instead of 10 minutes) using a warlock spell slot.

Test of Firaleene: (Prereq: 14th level, Sphinx Patron) Once per day, you can age a creature 10 years forward or backward in time. An elderly creature or a creature reverted to a child has their STR, DEX, and CON scores reduced to 8. The DM can change this number depending on a creature's race or current age. For instance, an elf might remain unaffected while a child might increase their ability scores if they increase in age. This transformation persists for a number of hours equal to your CHA modifier.

Page of Mystery: (Prereq: Sphinx Patron, Pact of the Tome) Your Book of Shadows gains a new page that changes its text whenever you finish a long rest. The text will help you with an event that will occur later that day. Roll 1d10 at the end of each long rest and record the result. You can add the result as a bonus to any one skill check, saving throw, or attack roll of your choice until you finish another long rest. The modifier can be applied after a roll is made but before you find out the results of the roll.

Treasure from the Sphinx: (Prereq: Sphinx Patron, Pact of the Blade) You can summon a magical item loaned from the sphinx's treasure hoard as your pact weapon. A pact weapon summoned this way deals a bonus 2d4 psychic damage each time it deals damage. Summoning this weapon takes a warlock spell slot and lasts for 10 minutes.

Sister of Fionnghuala

Fionnghuala is the fey goddess of the swanmays, sisterhood, and the protection of good fey. She usually grants her patronage only to women, but may make an exception for a man who demonstrates worthy qualities and dedication. The swanmays themselves are all women who exhibit extraordinary grace and skill as hunters who have the ability to transform into swans. They have powers over wind and water and other fey magic. Fionnghuala shares some of these powers with creatures who enter pacts with her, though they never achieve the full powers of a true swanmay.

Warlocks with this patron grow white feathers on their shoulders and the crown of their head. A halo around the warlock is filled with saturated color and is blurred slightly in romantic hyperbole.

I wanted to create a variety of warlocks for Warlock Week, so I wanted to include a non-evil one. I wanted to make one for Nathair Sgiathach, the god of faerie dragons, but a Google search showed that someone already made such a warlock! Who knew. Anyway I wanted to do a different take on the Swanmay and make them more interesting/useful than their 3e counterpart. The "golden city" comes from the Tsar Saltan Swan Princess fairy tale, not D&D lore. Note that the swan you turn into has the stats of a Hawk, not a Giant Hawk. It's mostly for mobility, not combat.

image credit: Terese Nielsen

Swan’s Grace: At 1st level, you are gifted with supernatural beauty and an affinity for animals from Fionnghuala. You gain proficiency in Animal Handling and Persuasion and double your proficiency bonus with such skill checks. You can speak with birds at will as if with the Speak with Animals spell.

Token of the Swanmay: At 6th level, you receive a token as a gift from Fionnghuala for your service to the Swanmays. The token can be anything from an acorn or feather to a golden coin. As long as you are in possession of the token, you can transform at will into a swan as if using the Wild Shape ability. The swan has the same statistics as a Hawk.

Resist Evil: At 10th level, you become a defender of good. You have advantage on saving throws against spells and abilities of evil creatures, and are immune to effects that would induce the charmed condition.

Golden City of Fionnghuala: At 14th level, you can cast Demiplane once per day to make a gateway to the golden city created for the Swanmays, where there is always a Heroes’ Feast (as per the spell) waiting for guests. The wonders of the island city include intelligent, talking animals, golden fruit and nuts in the bountiful trees, and white towers topped with domes of gold. The city is guarded by 33 aquatic elf fighters. There is a 25% chance that Fionnghuala herself is present here and can answer questions as if with a Commune spell.

Invocations:

Song of the Swan: (Prereq: 8th level, Fionnghuala Patron) Once per day, you can use your action to sing. As you do, good creatures within a 60 ft. radius gain advantage on attacks and on saves against the frightened condition. Evil creatures in a 60 ft. radius instead gain disadvantage on attacks and on saves against the frightened condition. Non-evil and non-good creatures are unaffected. Each round, you can maintain the song using your bonus action and your concentration. The song lasts up to 1 minute.

Presence of Fionnghuala: (Prereq: 6th level, Fionnghuala Patron) You can cast Calm Emotions a number of times each day equal to your CHA modifier.

Restful Slumber: (Prereq: 6th level, Pact of the Chain, Fionnghuala Patron) While you have a Sprite or Pseudodragon familiar summoned, the saving throw DC of your familiar's poisoning ability is increased by an amount equal to your CHA modifier.

Unnatural Beauty: (Prereq: Fionnghuala Patron) Creatures have disadvantage on saving throws against effects you control that would induce the Charmed condition.

Bow of the Swanmay: (Prereq: Fionnghuala Patron, Pact of the Blade) You can summon a longbow for your pact weapon. Evil-aligned creatures damaged by your pact weapon take an additional 1d6 force damage and are blown 10 ft. away from you by a rush of wind. Non-evil creatures do not take extra damage and are not moved.

Binder of Acererak

Acererak the Devourer is a vestige of a demilich that sought to fuse with the negative energy plane and devour all life force on the material plane. Needless to say, he failed in his goal but his existence and ambition lives on as a vestige. Warlocks that make their pact and bind to this vestige can share a glimpse of Acererak's ancient power, and eventually finish a transformation into a minor lich themselves. Acererak entreats his disciple to seize power wherever it can be found.

Warlocks with Acererak for their patron gain an appearance of death, becoming cold to the touch, pale, and gaunt. Some warlocks might grow gems that replace their teeth or eyes (such gems turn into normal body parts if removed and regrow in 1d4 days).

I wanted to do one of the vestiges as a subclass and I felt that Acererak allows me to make a generic undead patron as well. Warlocks could use this as a template for any lich, vampire, or mummy lord patron with minor tweaks. The Tomb of Horrors invocation is also a fun callback I wanted to make, and I abstracted it enough so that creatures sent there don't ACTUALLY have to run the module. The reference to Tenebrous, another vestige, is because Acererak owes his rise to power to him. I was a bit nervous about giving a player a phylactery at such a seemingly low level, so I added the fact that they are essentially put out of commission for a while if they try to abuse their phylactery by repeatedly dying.

image credit: Elisabeth Nagurnaya

Guise of Undeath: At 1st level, you register as an undead for spells that detect undead as well as to other undead. Undead of CR 2 or less will not attack you unless you attack them first.

Paralyzing Touch: At 6th level, you can make a Melee Spell Attack using your action against a creature within 5 ft. of you. If you hit, the creature takes 2d8 cold damage and must make a saving throw against your spell save DC with a +5 bonus to their roll. If the creature fails the saving throw, the creature becomes paralyzed for 1 minute. The creature can make a new saving throw at the start of each of their turns (without the bonus to their saving throw from before), ending the effect on a successful save.

Frightening Gaze: At 10th level, you can use your bonus action to direct your gaze at a creature you can see. That creature must make a WIS saving throw against your spell save DC or become frightened for 1 minute. The creature can repeat this saving throw at the start of each of their turns, ending the effect on a successful save. Creatures that succeed at a saving throw against your Frightening Gaze are immune to its effects for 24 hours.

Pallor of Undeath: Also at 10th level, you gain resistance to necrotic damage, immunity to poison damage and immunity to the poisoned and exhaustion conditions.

Lich Transformation: At 14th level your transformation into a minor lich is complete. Your type changes to undead and you gain a phylactery that costs 1000 gp to create. If you die, your body regrows in 1d10 days within 5 feet of your phylactery as long as it remains intact. Your phylactery takes a while to reach full power after rejuvenation. If you die again within 60 days of your last rejuvenation, you instead regrow your body in 1d10+50 days. Your phylactery can have any appearance but is generally between the size of a ring and a jewelry box and is destroyed if it takes 15 or more damage at once from a single source.

Invocations:

Return to the Tomb: (Prereq: 15th level, Acererak Patron) Using your action and the sacrifice of a diamond of at least 100 gp in value, you can force an intelligent humanoid creature of Large size or less to make a WIS saving throw against your spell save DC or else be transported to a random room in the Tomb of Horrors. The creature makes an INT check every 10 minutes with a DC of 30 minus the creature's HD. When the creature makes 3 total successful saves, the creature escapes with their lives and is teleported back to their original location. If the creature makes 3 failed saves before 3 successes, the creature either dies or becomes trapped in the tomb for eternity. You can use this ability once per day.

Acererak's Resistance: (Prereq: Acererak Patron) You gain resistance to cold and lightning damage.

Ambition of Tenebrous: (Prereq: 6th level, Acererak Patron, Suggestion spell) When you cast Suggestion, you can target an additional number of creatures equal to your CHA modifier.