Sentient artifact idea: Blood of Shadows (super rough draft)

History: Long ago, there was a war between agents of light and darkness, with supernatural entities walking the earth on both sides (like angels and devils). The leader of darkness was broken, with all of their being except their blood destroyed.

(The nature of this being: they are from the negative plane, and want to snuff out existence entirely. They corrupt people to evil, and create undead and summon shadowdell creatures to fight for them. They cannot create, but simply corrupt what exists. People using the artifact are just means to an end. It will corrupt and harm non evil users, and use evil users. The goal is to get a powerful body again through the life forces of people, likely a large amount.)

The blood is encased in a white globe, with a band of lead wrapped around it. When struck with radiant magic, words light up (don't have my notes on me so I can't quote them). The sphere is found in a vault, at the foot of an angelic statue whose hands have fallen apart.

The holder is compelled to enter the shadowfell. There they find a dark opposite, a large skeletal figure in a robe, hands outstretched like the angelic counterpart before its hands fell apart. When placed in the hands, it will animate and break the shell open, releasing the blood.

Movement: The blood is sentient and able to move on its own, albeit slowly.

Attunement: It can only be attuned to if you're under 10 hit points, and only if you've suffered piercing or slashing damage, as it attempts to enter the blood stream. You need a successful save as well to attune, probably constitution. Otherwise, you'd take necrotic damage and it would leave the host.

Each attack does a bonus 1d8 cold and 1d8 necrotic damage.

Damage done is stored as stolen life, used for various purposes, such as: -control undead -corrupt/control living creatures -reform creatures. -reaction to block damage

There will also be means of creating vessels to store creatures bodies/souls (thinking like the Matrix, where the bodies are like batteries), as a means of harvesting their life force.

There will also be a cap to the stolen life, with ways to increase it (not precisely sure how yet).

Constitution score is raised to 20. Further, the user can spend a shot rest to move stats around.

Devils sight for 60 feet, adding on to dark vision range.

Desires of the artifact: -Attuned creature must commit evil act daily -attuned must spread corruption (in the form of corrupting living matter) -attuned must persuade others to commit evil.

Failure to act on desires results in: -lost hp/max hp -leaving, causing damage in the process -taking control of the host body -take away benefits, leaving only negatives -imposed hopelessness, other flaws (perhaps withdrawal symptoms).

Just trying to play with flavor and ideas, and will flesh out numbers and such later.

Thoughts?