Armillaria of the Shadowfell

"This Armillaria grows for miles in the Shadowfell, desperately trying to consume everything it touches. How'd you even get your hands on this stuff?"

This single, black mushroom emits dark wisps of shadowy smoke. 

Armillaria of the Shadowfell has 7 charges. When you cast a spell that requires concentration, you can expend up to 5 charges to have the Armillaria maintain that concentration. The amount of charges expended must be equal to the level of spell cast. When charges are expended in this way you take 2d6 necrotic damage for every charge expended. While being used in this way, the Armillaria will hold concentration for 30 seconds, another charge can be expended to maintain concentration for another 30 seconds. If you take more than 25 radiant or fire damage in one round, the Armillaria's concentration is lost. If you take more than 125 damage of any type in one round, concentration is also lost. 

While attuned, 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 modifier or spell save DC: inflict wounds       (1 charge), vampiric touch (3 charges), or contagion (5 charges).

You regain charges when you spend 1 minute to spread spores to the body of a creature that has been dead for no longer than 7 days. You regain those charges relative to the creature's size:  1 for Small, 2 for Medium, 3 for Large, and 4 for Huge, any body larger than huge regains all charges.

Mycotic Attunement: To attune to Armillaria of the Shadowfell, it must be ingested by the user. Attunement takes an hour, as the fungus spreads throughout the body. At the end of the attunement process, the user's body has sprouted with fungal rot. The fungus can be cleared or removed during a short or long rest, but will grow back in 1d6 days; unless attunement is broken. If the user is killed, the attunement is broken and the fungus is destroyed.

Breaking Attunement: If attunement is broken without the use of a "Remove Curse" spell, it is an arduous and painful process where the fungus must be remove the fungus from all orifices. The process requires six consecutive DC 18 Wisdom (Medicine) checks over the course of three days. A failed check results in a level of exhaustion. 

Notes: requires attunement by a Druid or Ranger