You were once a normal being. You retain one trait from your former race. Except you are unable to retain any traits that go against an existing trait or relate to gods or demons.

You know common and another language of your choice.

Due to the blood of a god your constitution increases by 2 and your intelligence increases by 1 from the blood of a devil. Gods are nearly impossible to kill due to their high constitution and strength, you inherit some of this constitution. Devils are known for their conniving nature, you inherit your intelligence from this and your immense lifespan (Plenty of chances to learn).

Blood Spawns were not created by gods or demons; rather, they were formed from their viscera, and, as such, they live until they are killed, either by poison or blade.

They are always neutral evil as they do not harbor emotions or morals. This alignment may change (With DM's approval) overtime if emotions or morals are developed.

Your base size is small.

Due to your abnormal creation and small stature, your weight is practically non existent. Typical weight is 1lb to 3lbs.

Your base walking speed is 35 feet due to your low weight. Your burrowing speed of 20 feet and climbing speed of 20 feet are due to your innate ability to slightly adjust your body's contours to match the ground to climb and form small spikes (Used to push forward like the monsters in the movie Tremors) when burrowing. You cannot swim. Instead you float still, unable to move.

You cannot wear armor (Including shields) as your physical form isn't solid enough for that; however, your Unarmored AC equals 11 + your constitution modifier. This total increases by 1 at levels 4, 8, 12, 16, and 20.

You are capable of solidifying a part of your gooey and bloody body into a tendril as an attack action, allowing you to grab anyone or anything within 10 ft. If you decide to grab a creature, you must make a grapple check.

Due to the gods and devils condemning your existence, you cannot be a class that receives their support. If you do, the gods or devils will appear in the world to end your life.

Due to your years of experience avoiding gods and devils along with your tiny stature, you are proficient in the stealth skill.

Typical restraints can't hold you. While you are conscious you may slide out of any rope or restraints. You can also move through a space as narrow as 1 inch by squeezing but you take 1d4 damage.

Part of the energy that went into your creation bubbled up from the Abyss. Your type is Fiend. You have advantage on saving throws to being charmed, and magic cannot put you to sleep. You also have Dark vision of 30 ft.

Due to the regeneration abilities of gods you are Immune to sickness and  have advantage on saving roles against being poisoned.

Due to the regeneration abilities of gods, on a short rest if you roll for a hit die the amount of hit points regained is double the amount rolled plus constitution modifier.

As all healing spells are either divine or demonic in nature, you are unable to be healed by spells since the gods and devils condemn your existence. In fact, all healing spells will do 1d4 of damage to you.