Tainted Blood

As a Tainted Blood sorcerer, your abilities are the result of some arcane meddling that occurred long in the past.  One of your ancestors was exposed to raw magical energies, and the effects of that exposure have echoed down through the generations to solidify in your blood.  Some bloodlines were tainted by magical accidents or catastrophes of the distant past.  Others were the result of sinister experimentation at the hands of dark wizards or necromancers.  Regardless of its source, the blood that runs through your veins is infused with magic, and your powers are the result.

Boiling Blood

As a result of your affliction, your body has a physical reaction whenever it comes close to another potent source of magic.  When you are within 30 feet of an aberration, celestial, elemental, fey or fiend, your body becomes noticeably warmer and a tingling sensation develops within your mind.  This feature does not tell you how many of these creatures are nearby, nor does it reveal their types or locations.

Arcane Dowsing

At 1st level you know the spell detect magic, which does not count towards the number of Sorcerer spells you know, and you can cast the spell without using a spell slot.  When you do so, the spell does not require your concentration, and magical sources are revealed to you over a radius of 60 feet, rather than 30.

Once you cast the spell without using a spell slot, you may not do so again until you have completed a long rest.

Sanguimancy

Starting at 6th level you are able to expend your body's vitality to empower your magical capabilities.  Whenever you complete a short rest, you may expend hit dice in order to regain expended spell slots, rather than lost hit points.  You may expend up to five hit dice using this feature, regaining an equivalent number of expended spell slot levels.  For example, if you expend two of your hit dice using this feature, you may regain one 2nd-level spell slot or two 1st-level spell slots.  You do not regain any hit points from hit dice expended in this way.

In addition, whenever you expend hit dice to regain hit points as part of a short rest, you may spend 2 sorcery points to reroll any of the dice, but must take the second number rolled.  You may not use this feature again until you have completed a long rest.

Arcane Absorption

Starting at 14th level you learn to redirect the magical energies of an enemy's spell and absorb them.  As a reaction when you are targeted by another creature's spell, you may expend a number of sorcery points equal to the level of that spell.  The spell's effects against you are completely nullified, and you instead regain 1d6 hit points for every sorcery point expended (up to 9d6 hit points.)  If you do not have enough sorcery points to match the level of the spell targeting you, the spell is not nullified and your reaction is wasted.  If the spell targets multiple creatures, the effects are only nullified for you, and the spell's other targets are affected normally.

Flux Aura

By 18th level you have attuned your body to the magical forces that it produces, and gained limited control over them.  As a bonus action you can extend an aura of arcane flux to occupy a sphere with a radius of 60 feet, centered on you.  The aura moves with you and lasts for one minute, dissipating early if you are incapacitated or if you die.

Creatures other than yourself within the aura have disadvantage on their spell attack rolls, saving throws against your spells, and on concentration checks made to maintain their spells.  Inversely, you make spell attack rolls, saving throws against another creature's spells, and concentration checks to maintain your spells, with advantage while within the aura.  A creature outside of the aura cannot target a creature or location inside the aura with their spells.  When you first extend the aura, you may designate any number of creatures you can see who will not be affected by it.

Once you have activated the aura, you may not do so again until you have completed a long rest.