Fiend Bloodline

Demons and devils are some of the greatest forces in the multiverse, one born evil order and lead by malicious tactician, the other born of hatred and chaos commanded by madness. Fiends exist and many planes, most predominately the nine hells or the abyss, though fiend such as yugoloths exist on any plane, some fiends from the hells or abyss even venuture to the material plane in service of their demonlord or archdevil.      

Fiendish Spells

Starting at 1st level, your half fiend nature causes your spells to ignite foes in hellish blazes. You learn additional spells when you reach certain levels in this class, as shown on the Fiendish Spells table. The spell counts as a sorcerer spell for you, but it doesn’t count against the number of sorcerer spells you know. These spells can’t be replaced when you gain a level in this class.

Fiendish Spells

Fiendish Ancestry

Also at 1st level, fiendish blood courses through you, this blood makes you harder to kill than most and more durable. Your unarmored armorclass equals 13 + your Dexterity modifier, and you have resistance to poison damage and have advantage on saving throws against being Poisoned. Additionally, you can read, write in, and speak your choice of Infernal or Abyssal, and when you make make a Charisma ability check or skill check made to interact with a fiend that innately speaks your language choice you may add double your proficiency bonus to the roll.  

Dark One's Resistance

Starting at 6th level, you gain resistance to fire damage and immunity to being poisoned. Additionally, you may choose a damage type once after a short or long rest, you gain resistance to the chosen damage type until you choose a different one with this feature, though magical or silvered weapons ignore this resistance. 

Fiendish Summons

Starting at 14th level, once after a long or short rest, you may summon a fiend creature of challenge rating 10 or lower. This fiend lasts until you use this feature again, takes initiative as a normal creature would, but requires your bonus action to be expended for it to take an action besides the dodge, disengage, hide, or dash action. This fiend retains all it's other features from its stat block.

Dark One's Will

Starting at 18th level, you have immunity fire and cold damage, you gain a flying speed equal to your walking speed, and spells you cast add your Charisma modifier to the damage they deal.