Harvester

Warlock. Summoner. Corrupter. Harvester. Witch. All these and more make up the titles given to these auspicious casters. Though they generally come from a history of wizardry, any arcane skill may give rise to a Harvester, as their commitment is not to learning or knowledge, solely power. With an emphasis on long term curses, drains, and summoning powerful allies- for a price, these men and women give an ultimate sacrifice to become a Harvester: Infusing their very soul and body with the power of the Twisting Nether, Fel magic. 

Demonic Attunement

Upon taking this subclass, your character must undergo some form of Ritual. Either you summon a demon and make a pact, or go so far as to absorb their soul into your own, or even consume their blood- you must taint your being with their energy. Doing this unlocks the attunement of additional spells, such as Fel Bolt. 

In addition, upon completion of this ritual, you will gain the ability to summon a Demon as your permanent companion, as if summoned by the Find Familiar spell, with the exception that it may attack. It is then bound to your service forever. If it dies, it may be resummoned by a ritual lasting 10 minutes. Alternatively, you may expend a soulstone to instantly summon your Demon to you. At level 2, you gain the ability to summon an Imp. At level 6, you may summon a Voidwalker. At level 11, you may summon a Felhunter. At level 15, you may summon a Felguard. At level 18, you may summon a Doomguard. Only one of these summons may be active at a time. You may only preform the ritual once per long rest.

Black Harvest

Your magic allows you to siphon life from all around you, including your demonic servants. You gain the following actions.

Drain Life: Once per day as an action, you may concentrate on a target within 60 feet. Make a ranged spell attack. On a hit, you siphon their life force, dealing 6d6 Necrotic damage. This damage increases as you level, raising to 11d6 at level 11, and 16d6 at level 16. You then heal for half the damage taken. Your demons count as willing targets for this effect, and you may automatically hit against them. However, this will kill them, regardless of damage dealt. 

Siphon Life: Once per day as an action, you may concentrate on your demonic companion, or other demons or fiends who count as allies to you within 60 feet. You may then drain any amount of your own health as Necrotic damage to heal them for the amount taken.

Pact of the Legion

Any demon or fiend attempting to attack, or otherwise harm you, must succeed in a Wisdom saving throw against your spell save DC. Should they fail, they cannot go through with the action, and are stunned until the beginning of your next turn. In addition, demons summoned via Summon Lesser Demons or Summon Greater Demons are friendly to you and obey your commands without question. You may also choose which demons are summoned by said spells. Finally, you gain resistance to Fire damage, and advantage on Wisdom saving throws.

Metamorphosis

Once per long rest as an action you may enter a state of demonic fury, enhancing you and your demon. You gain the ability to fly at 60 feet a round, and your body changes into a large winged demon cloaked completely in shadow, your true features unable to be made out. All enemies who can see you must make a DC 15 Wisdom saving throw or be frightened of you until the effect ends. Enemies who fail may remake this save at the start of their turn, and enemies who succeed in this saving throw are immune to this effect for the next 24 hours. Your demon gains the same terror effect. In addition, any creature who ends their turn within 10 feet of you or your demon will take 4d6 Fire damage. You gain immunity to fear and psychic damage during this transformation.