Bloodstone Orb

Bloodstone Orb Epic Arcane Focus Use: Whenever you fail a saving throw against spell or magic effect caused by a celestial or fiend, you may reduce the Bloodstone Orb’s rank and take that much necrotic damage and succeed on the saving throw instead.

Bloodstone Orbs are enchanted foci that pulse with abyssal magics. When fed the blood of demons, the orb's power permanently grows, as does the danger of wielding its powers. Celestial creatures see these objects as blasphemous and seek to destroy them, while devils and demons seek to claim its powers for themselves.

Properties

When fed the blood of a demon, the Bloodstone Orb's powers grow by one rank, to a maximum rank of that demon's maximum Hit Dice.
When used as a part of any spell to impose control over a demon, the Bloodstone Orb imposes Disadvantage on the demon's save to resist as long as the orb's rank is greater than or equal to the maximum Hit Dice of the demon. If the demon still succeeds on the saving throw, you take necrotic damage equal to the orb's rank.
Whenever you fail a saving throw against spell or magic effect caused by a celestial or fiend, you may reduce the Bloodstone Orb’s rank by an amount equal to the creature's proficiency bonus. You take that much necrotic damage and succeed on the saving throw instead.
The necrotic damage from these effects ignores resistance and immunity.
A sorcerer, warlock, or wizard can use the Bloodstone Orb as a spellcasting focus.