Zeria's Ring (requires attunement)  I bone ring covered in mycelium and lichen, when placed on the hand and then attuned, the bone absorbs into the skin and wraps around the finger leaving the moss and fungi left to wrap around the finger in a ring esc look 

This ring was imbued with Zuggtmoy's tainted magic just before she was initially sealed away with the crystal flowers. The Gift was a last-ditch effort to support and power a single champion just enough to one day be able to free her.  As the ring grows in power , the more mushrooms and spores begin to grow along their form.  Trying to take the ring off or trying to stop the spread only speeds it up.

Dormant:

User has +1 to spell attack bonus and spell save DC.

Enthralling Grasp: Once per day when you kill a non-undead humanoid creature in any way you may use a bonus action to raise their corpse from the dead as a Ghoul. You can use a bonus action is subsequent turns to issue verbal commands to this creature. At the end of the day you may choose to use this feature to maintain control of the Ghoul or the ghast crumbles into dust. This use does count as your daily use of this feature.

Awakened:

User has +2 to spell attack bonus and spell save DC.

You gain resistance to necrotic damage

Touch of Undeath: When an undead under your control hits a creature with a melee attack they deal an additional 1d6 necrotic damage

Exalted:

User has +3 to spell attack bonus and spell save DC.

You gain immunity to necrotic damage.

When you use the Enthralling Grasp feature the creature raises as a Ghast instead. Also, you can use the feature twice each day.

Your Touch of Undeath feature now does 2d6 necrotic damage. 

You are now considered Undead as well as your other racial tags. 

Notes: Requires attunement by a Druid