Warlocks that study adherency embody the fel energy within themselves, wagering their humanity and in extreme cases, life, to become a conduit of fel magic and defend themselves with a tougher body. If there was no humanity in them to begin with, all the better!

Additionally Learned Spells

2nd-level Study of Adherency feature

Your area of study has given you additional spells to utilize against those foolish enough to be your foes. At the following Warlock levels, you gain the following spells, and they do not count towards your maximum number of Warlock spells known.

Warlock Level - Spells

2nd - Chaos Bolt, Protection from Evil and Good

4th - Enhance Ability, Shatter

6th - Haste, Spirit Guardians

8th - Elemental Bane, Fire Shield

10th - Banishing Smite, Destructive Wave

Soul Engine

2nd-level Study of Adherency feature

Taking the first step towards Adherency is to dedicate to the fel powers you seek to wield. You bore a well of fel power into your form, or tap into it if you already had one - this creates a cycle of life and disorder within your very core. Creatures who can detect magic will also detect this power within you, and register it akin to a demon's supernatural aura. This effect cannot be turned off, but may be suppressed as an action, during which you cannot access any feature which requires a resource or somatic component. You may reignite the Soul Engine as a 1 Minute ritual.

Heart of Fel

2nd-level Study of Adherency feature

Once you first create the Soul Engine within yourself, you gain the following features:

• You count as a Fiend for the purposes of attacks, spells, and features that have no effect on your original race, if you do not already.

• You gain an additional +1 to your maximum hit points for each warlock level you have.

• You learn the Green-Flame Blade cantrip. This does not count against your Warlock cantrips known.

• Choose either Melee or Ranged weapon attacks. When you make an attack of that choice, you may use your Intelligence modifier instead of it's normal ability score bonus to the attack's hit and damage rolls.

In addition, you will choose between one of the two following options:

• You gain proficiency in Light and Medium armor, and Martial weapons. You may conduct the somatic component for your spells with an equipped weapon.

• Your AC is now calculated as 13 + Dexterity Modifier while unarmored. Your movement speed increases by 10 feet.

Fel Conduit

6th-level Study of Adherency feature

When you would cast a spell that deals damage to at least one target, you may deliver the spell through a weapon attack. When you do so, make an attack roll with the respective weapon.

• If you hit, you will deal the weapon's normal damage, and the spell will trigger on the target. If the spell requires an attack roll to affect them, ignore it and consider the attack roll a hit (A critical hit will follow critical hit rules for the weapon and the spell). If the spell requires a saving throw, the target makes the saving throw, but at disadvantage.

• If you miss, the spell will instead center on or target you, erupting from your chosen weapon attack regardless.

In addition, you are considered resistant to any damage you deal from your own spells, unless you are already considered immune.

Deepening Reserve

10th-level Study of Adherency feature

Your Soul Engine commits more of your essence to raw power. You gain the following features:

• You may use Life Tap one additional time between long rests.

• At the start of each of your turns, you gain temporary HP equal to your proficiency bonus. You instead lose this much health every minute if your Soul Engine is suppressed.

• You may ignite your Soul Engine as an action, ignoring the previous ritual.

• If you are proficient in Medium armor, you become proficient in Heavy armor and Shields as well. If you are not, you now calculate your AC as 15 + Dexterity Modifier while unarmored, and your movement speed increases by another 10 feet.

Felflame Imbuement

14th-level Study of Adherency feature

Green fire licks from your drawn weapon, and yet you feel no burn, no pain. You become immune to fire damage. Any fire damage that you deal ignores fire resistance, and creatures immune to fire damage are considered to be resistant.

Expulsion

18th-level Study of Adherency feature

A sight to behold, your Soul Engine is now visible to the naked eye, burning a light through flesh and bone. You add your Intelligence modifier to your Armor Class.

As an action, you can gather the reserved power of your Soul Engine and erupt it from your being, either from your chest, mouth, hand, or eyes, rocketing out as raw energy. Creatures within either an 60 foot line or 20 foot cone must make a Dexterity saving throw against your spell save DC, taking 15d10 Fire damage on a failure, or half as much on a success. Afterwards, your Soul Engine becomes suppressed and cannot be ignited again for 10 minutes. You then cannot overload the Soul Engine in such a way again until after completing a Long Rest.