The Pact Primeval
The one event, at the beginning of the world, that allowed devils to make pacts with mortals, tricking them into selling their souls, indeed was by itself nothing else than the signing of a pact - a pact between Asmodeus and the gods that is known as the Pact Primeval.
One might think this pact only affected those it was signed by, but indeed its magic could be felt by a great number of people as it created one of the fundamental aspects of the world, the dichtomy between devils and celestials. Soon after the Pact Primeval was signed, devils started making pacts with humans, granting them power in exchange for their souls. But it was not just devils who started making contracts, the latent magic of the Pact Primeval granted other bloodlines - like those that had their ancestors witness the signing of the Pact Primeval - the ability to make pacts to some extent as well, which they made great use of, spreading the idea of pacts to achieve power further around in the still young world.
Some of these bloodlines have survived to this day, and still are able to use the latent magic of the Pact Primeval to become powerful spellcasters and to make contracts with others similar to the typical pact with a devil.
Extended Spell List
At 1st level, the latent magic of the Pact Primeval grants you access to an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.
| Spell Level | Spells |
|---|---|
| 1st | dissonant whispers, sanctuary |
| 2nd | zone of truth, Nystul's magic aura |
| 3rd | life transference, sending |
| 4th | Leomund's secret chest, locate creature |
| 5th | geas, modify memory |
Born to Negotiate
At 1st level, you gain proficiency with both the Deception and Persuasion skills. Your proficiency bonus is doubled for any skill check you make that uses either of these proficiencies. In addition, you gain proficiency with calligrapher's tools.
Moreover, when you cast a Warlock spell using a Warlock spell slot and target one creature with it, you can roll a Charisma (Deception) check contested by the creature's Wisdom (Insight) check. On a success, the creature believes you are casting a harmless spell and has disadvantage on the first saving throw against this spell. On a failure however, it has advantage on the first saving throw against this spell.
Bound by Signature
Also at 1st level, your signature, written with your own blood, becomes imbued with magic. When you sign a contract with another creature, you can force this creature to make a Wisdom saving throw against your spell save DC. On a failure, it becomes charmed by you for 24 hours, feeling compelled to do anything necessary to not break their part of the contract, although itt cannot be compelled to physically harm itself or another creature friendly to it in this way.
The duration of the charm increases to 7 days at level 6, to one month at level 10 and at level 14 it lasts for an infinite amount of time. The charm ends early if the contract ends, for example because the creature fulfilled its part. Only one creature at a time can be charmed by you in this way.
Infernal Pact
At 6th level, you learn to set up a pact to bestow minor magical powers to other creatures, modeled after the pacts with devils enabled by the Pact Primeval. Setting up a pact requires one willing creature to participate in the ritual-like process, which takes 1 minute and ends with both of you signing a magical pact with your blood.
With this pact, you grant the creature the ability to cast a Warlock cantrip you know at will for 1 hour, as well as the ability to cast a 1st-level Warlock spell you know once within the next hour without expending a spell slot.
Once you have used this feature, you cannot use it again until you finish a short or long rest.
At 10th level, you can grant access to a 2nd-level Warlock spell, and at 14th level you can grant access to a 3rd-level Warlock spell in place of the 1st-level spell.
The Fine Print
Starting at 10th level, when you successfully use your Born to Negotiate feature to impose disadvantage on a creature's saving throw against a spell cast by you, you can deal necrotic damage equal to your Charisma modifier plus your Warlock level to that creature as you hide a clause that demands a part of its soul as payment within your negotiations. If a creature takes this damage, it cannot regain hit points until the start of your next turn.
In addition, when you read a contract or pact, you automatically know all its clauses, including those hidden deep within the fine print, even if magic was used to try to hide or obscure them.
Greater Infernal Pact
At 14th level, when you make an Infernal Pact with another creature, you can also grant that creature the ability to use an Eldritch Invocation you know for the duration. If the Eldritch Invocation has prerequisites, the target must be a warlock itself and fulfill the prerequisites. Moreover, whenever the creature you made the pact with reduces another creature to 0 hit points, you can use your reaction to give it temporary hit points equal to your Charisma modifier plus your Warlock level.
Master the Dungeon, "How To Make a Patron for a DnD Warlock" by Jae