Are night hag's heartstones Adventurers League legal?

Question

According to this post by Jeremy Crawford, a Night Hag's Heartstone is meant to work for hags but it is a DM's choice whether it works for PCs.

The Monster Manual (p.177) describes the Heartstone's abilities as:

Heartstone: This lustrous black gem allows a night hag to become ethereal while it is in her possession. The touch of a heartstone also cures any disease. Crafting a heartstone takes 30 days.

Does that rule-it-out or rule-it-in as being Adventurer's League legal for PCs to own, use and or trade?

We are looking for RAW/RAI guidance or precedent. Our assumption is that etherealness is only usable by the night hag - but Cure Disease would be usable by PCs.

This is particularly relevant currently as the AL adventure (spoiler)...

Tomb of Annihilation has at least one hag who carries a Heartstone thus making it possible for PCs to obtain one.

Answer 1

I would say no.

The rule text specifically states "...allows a night hag to become ethereal" and the night hag has an action called "Etherealness", which requires a heartstone.

The stone does not provide this ability, it only enables the night hag to use her ability.

On a more balance-related note, it would be an amazingly good and game-breaking item. It's unlimited castings per day of Etherealness (a level 7 spell).

As for the cure disease effect... Looks like it would work, RAW. Not terribly game-breaking either (though most diseases would obviously become a non-issue).

Answer 2

No

But not for the reason you think. It might be used as an infinite cure disease, that's ambiguous (as Crawford states) and probably up to the DM, even in AL.

The reason for my No is: players can't actually get it. Permanent Magic Item (Season 7 Dungeon Master Guide for AL, p. 4) states

A permanent magic item can only be awarded if it, or the random magic item table it’s rolled from, is mentioned in the encounter in which it is found.

Note that the hags simply having the magic item doesn't make it "awardable", for example, earlier, King Groak is stated

King Groak (a gold-skinned grung elite warrior with a circlet of blasting [...])

But it is stated again in the Treasure

Treasure. King Groak wears a circlet of blasting,

The Gold and Mundane Rewards (from DMG Guide for AL) also states

As a general rule, items and treasure can’t be awarded unless it is described under a ‘Treasure’ subheading

I've looked through the ToA and the Heartstone is not described under any Treasure subheading, unless I missed something.

Answer 3

I think the text is pretty clear and unambiguous.

The heartstone enables the pre-existing etherealness ability of a Hag. If you are not a hag, the heartstone does not do this for you.

The touch of a heartstone cures any disease. There is no limitation on who might be holding the heartstone or how many prior times it has been used in this way.

So, based on this, RAW, if the PCs obtain a heartstone, they can cure any disease at-will, and an unlimited number of times.

The consequences, however, could be very interesting and subtle and long-term. Nighthags, for example, as fiends, are not permanently destroyed when killed on the prime material plane - they go back to their home plane and reform. They will probably want their heartstone back (grudge-match). Now, the party could do shady stuff like take that heartstone and cure only the diseases of the rich who would pay an hefty price. Might this begin to corrupt some or all of the party? hmmm...maybe. Might Hag then regret less or not at all the loss of her heartstone? Definitely maybe not.

On the other hand, imagine a nighthag is slain by an Oath of Devotion Paladin, and that paladin now takes that heartstone and goes from town-to-town curing every disease in sight - every disease - for free. That hag would be pissed - not only did they loose to a goodie-goodie, that goodie-goodie is now going around and eliminating disease. The plots and hard work of all the bad guys might suddenly get unraveled. The hag might get a phone call from her superior saying "This is your fault. You have one chance, and one chance only, to fix the situation. You don't want to know the consequences of failure". So the hag calls in some favors, gathers a possie, and big-time-grudge-match is on! Or, maybe if the afore-mentioned paladin repeatedly empties the disease ward of every hospital in an area often and in a sustained way, the doctors might pack up an move (ie: "guess we are not needed here"), the city sanitation practices cease (if there are no consequences for disease, why bother with prevention) - local healthcare becomes dependent on the traveling dude with the cure-disease-free stone. Then when Pally leaves for a while - oh boy - plague city. What would the Pally think of that as consequences for their well-intentioned actions?

Yep siree. Gold. Absolute plot gold. Far from breaking the game, it can make it 10x as interesting.