Wondrous Item

Legendary requires attunement by a cleric, sorcerer, warlock, or wizard of evil alignment Requires Attunement

This purple gem, once shattered and reforged with molten gold, is one of the legendary Quintus Gems and hums with necrotic energy through the gold that fuses its formerly-broken pieces together. It serves as the phylactery of Rhith, the Illithilich, who uses its power to both sustain himself and move his plans for revenge forward.   While attuned to the gem, you have resistance to necrotic damage, and you know the chill touch cantrip as if it were from your class's spell list.
If you are a wizard, you also gain a +3 bonus to your spell attack rolls and saving throw DCs of your spells while holding the gem.   An eerie, green flame erupts from this when you hold it, shedding bright light in a 20-foot radius and dim light for an additional 20 feet.
While holding the gem, you can use a bonus action to mentally snuff out or relight the flames.
While the flames are lit, you can use an action to make a ranged spell attack with it, using your spell attack bonus and spell save DC, out to a range of 30 feet.
When you do, the flaming gem emits a phantasmal skull that flies out to attack the target.
On a hit, the target takes 3d8 necrotic damage, and if the target is a creature, you regain hit points equal to half the amount of necrotic damage dealt.
The skull disappears immediately after the attack.   Random Properties. The Purple Quintus Gem has the following random properties:

• 1 minor beneficial property
• 1 minor detrimental property
• 1 major detrimental property

Spells. The gem has 8 charges and regains 1d3 + 1 expended charges daily at dawn.
When you reduce a humanoid to 0 hit points, the gem regains 1 expended charge.
While holding the gem, you can use an action to expend 1 or more of its charges to cast one of the following spells from it, using your spell attack bonus and spell save DC: bestow curse (1 charge), circle of death (4 charges), confusion (2 charges), insect plague (3 charges), ray of enfeeblement (1 charge), or speak with dead (1 charge).   Bestow Greater Curse. When you cast the bestow curse spell while holding the gem using either the gem or a spell slot, you can choose to force the creature to make the saving throw with disadvantage.
On a failed save, the target is simultaneously cursed by all four of the spell's listed options.
Once this property has been used, it can't be used again until the next dawn.   Death Grip. While holding the gem, you can use an action to cast the finger of death spell from it, using your spell save DC.
Once the gem has been used to cast this spell, it can't do so again until the next dawn.   Curse. The gem bears a curse that affects any non-undead that becomes attuned to it.
Even if the attunement ends, the curse remains.
When you die while cursed in this way, you must make a Charisma saving throw against your own spell save DC.
On a failed save, or if the gem is more than 100 feet away from you when you die, your soul is immediately siphoned into it, leaving your body a vacant husk and unable to return to life by any means short of a wish spell.
On a successful save, your soul leaves your body and enters the gem, as if you had cast the magic jar spell, using the gem as a container.
You can only return to your body if it's holding the gem, but can otherwise gain the benefits of the spell as normal.
If your soul returns to your body, you return to life with 1 hit point.
While your soul is detached from your body in this way, your attunement to the gem is carried over to any other creature you possess for the duration.   Destroying the Gem. The only way to destroy the gem is to destroy Rhith while your soul is contained within the gem.
When you do, use your original body's statistics and abilities for your soul, with the exception that your hit point maximum is halved.
Use the illithilich stat block for Rhith's soul.
From outside the gem, this combat resolves instantaneously, regardless of how much time passed within the gem during the battle.
If you die while within the gem in this way, your soul is forever lost within the gem.
If Rhith dies, the gem is destroyed and you return to your body with 1 hit point, regardless of where your body is at the time.