demonic bloodline

you were born to a demon mother, father, or both but your blood has been sleeping until now when it has been awakened and you have gone through changes but they come slowly, your mind is strong but your body is weak so the changes come slowly, but they are there you can feel it the pride, the lust, wrath, gluttony, greed, sloth, and envy so go and cause chaos go and conquer kingdoms, or fight for law and kill those that break it, or even get a lot of women (or men) and be in bed all day, your a demon DO WHATEVER YOU WANT!

Unholy Flames

Starting at 1st level, your power over Brimstone flames has begun. (Abyssal)When you deal fire damage with a spell, you may deal additional fire damage equal to your proficiency bonus.  (Infernal)You may make the damage for the spell's damage ignore resistances and to fire unless the creature is a fiend.

Brimstone Fireblast

 

When you deal fire damage with a spell, you may deal extra damage equal to your proficiency bonus.

 

Nine Hellsfire

 

When you deal fire damage with a spell, you may choose to ignore resistances to fire that the target(s) may have, unless the target is a fiend.

Brimstone Fireblast

once per short rest when you deal fire damage with a spell, you may deal extra damage equal to your proficiency bonus.

Nine Hellsfire

When you deal fire damage with a spell, you may choose to ignore resistances to fire that the target(s) may have, unless the target is a fiend.

demonic enchantment

at 6th lv you gain the ability to infuse flames into anything you are holding or even your hands, claws, and tail once per short rest as a bonus action for 30 minute and while it is enchanted it counts as a magical weapon.

minor manipulate fire

at 14th lv you can change and manipulate a cube of fire 5 feet in size for no cost you can change its shape and properties making it stick much like napalm, or make it rubbery and bouncy. 

multi casting

at 18th lv three times per short rest you can cast up to 3 cantrips with the same bonus action.

example: you are within 30 feet of your opponent you use chilling touch, shocking grasp, and mage hand all at once  to make a hand of magic that grabs the opponent and deals both 1d8 necrotic and 1d8 lightning damage.

you can also have up to 10 seconds in between each spell before the bonus action is up.

example: you are 30 feet away from your enemy you use mage hand on him and drag him to you where you grab his neck and use shocking grasp on him that deals 1d8 lightning damage, then you let him go and lift your other hand up to him and use acid splash.

feindish origin

you choose a demon/devil/feind you chose a trait from them and gain it, be it wings, or strong skin, or sharp claws, anything your DM will allow but here are two examples anyway.

Abyssal

 

Your skin turns a dark shade of red.  Your grow a tail similar to an imp's, which is a natural weapon that you can make unarmed strikes with, dealing 1d4 piercing damage on a hit.

 

Infernal

 

Your eyes look unnatural and you have slitted pupils.  Your hands grow claws, which are natural weapon that you can make unarmed strikes with, dealing 1d4 slashing damage on a hit.

these are two examples but please do more, and don't limit yourself.

Abyssal

Your skin turns a dark shade of red.  Your grow a tail similar to an imp's, which is a natural weapon that you can make unarmed strikes with, dealing 1d4 piercing damage on a hit you also gain 2 str and chr

 

Infernal

Your eyes look unnatural and you have slitted pupils.  Your hands grow claws, which are natural weapon that you can make unarmed strikes with, dealing 1d4 slashing damage on a hit which is nullified if you are wearing non fingerless gloves, you also gain 2 dex and chr.