Path of the Demon

You create a bond with a demon in exchange for more power. If you fail unconscious while raging you will need to make a constitution saving throw with the DC being 20 minus your charisma modifier minus your proficiency bonus. If you fail all rages will be consumed and you will be possessed by the demon you made your bargain with. Once possessed you return to full health and become consumed by bloodlust attacking any creature or person you see for 5 minutes. The possession ends if you fall unconscious again or the spell calm emotions is successfully cast upon you.

Demonic Seal

Starting when you choose this path at 3rd level a brand appears on your body marking you as property of a demon. You also gain immunity to fire damage while raging and as a bonus action while raging may make an additional attack as a bonus action. 

Demonic Rage

Starting at 6th level, when you enter rage your mind is no longer clouded allowing for spell casting up to 5th level while in rage.  You now learn 1 first level spell. You gain an additional first level spell once you reach 7th, 8th, 9th, and 10th level. You learn one 2nd level spell at 11th, 12th, 13th, and 14th level. At 15th, 16th, and 17th you learn a 3rd level spell. At 18th and 19th you gain a 4th Level Spell and at 20th level you gain a 5th level spell. When Picking spells you can pick from any spell class list. All spells picked with this class feature can be cast once per long rest and only while in rage. Spells cast with this feature are done so without needing material components and if require concentration they end when rage ends or when the caster takes more than a quarter of their max health in a single round.

Level	Spells Known per Level
	1st	2nd	3rd	4th	5th
1st	-	-	-	-	-
2nd	-	-	-	-	-
3rd	-	-	-	-	-
4th	-	-	-	-	-
5th	-	-	-	-	-
6th	1	-	-	-	-
7th	2	-	-	-	-
8th	3	-	-	-	-
9th	4	-	-	-	-
10th	5	-	-	-	-
11th	5	1	-	-	-
12th	5	2	-	-	-
13th	5	3	-	-	-
14th	5	4	-	-	-
15th	5	4	1	-	-
16th	5	4	2	-	-
17th	5	4	3	-	-
18th	5	4	3	1	-
19th	5	4	3	2	-
20th	5	4	3	2	1

Demonic Blood

The demon is pleased with your progress and allows you to channel more of it's power. Once you enter rage your blood begins to boil with demonic power. You gain (your class level divided by 4 rounded up)d12 temporary health everytime you enter rage. As a bonus when you gain this class feature you also can chose between gaining the tough feat or learning to summon a creature to aid you in battle. 

Feature

Gain the tough Feat

Summon slave

Spend an additional rage to summon a creature into battle. The creature is an extension of your will so no commands are necessary. This creature can take the form of either a Shadow Demon, Fire Elemental, Maw Demon, or a Pit Fiend

Demonic Transformation

Beginning at 14th level, when you enter rage your appearance takes a form more closely resembling the demon you made you pact with. While raging you add 2d6 fire damage to all melee attacks you make. You also gain advantage an all attacks against fiends.