True Polymorph on hagspawn

[Iampower]

So the group came across a hag coven recently and had finished it off. During the battle there were 3 children in the same area and 2 of them were killed, revived, and returned home. But the last is a hagspawn i threw in to mess with them. Now they have decided to keep her around until the bard gets true polymorph.
They plan to use true polymorph to turn her creature type from fey to human, or to be more precise, turn her from a hag to a human. Im personally inclined to allow this and maybe prepare a divine quest to make it truely permanent. But i was wondering if this is actually possible at all RAW or RAI. Hags don't have the shapechanger tag from what i tell.

[Eriol]

The rule I follow for most 9th-level spells is "it probably just works." 9th-level is massively powerful, culminating in "well, anything is possible with Wish" spell. I look at the other 9th level spells similarly: they probably bypass as many rules as Wish does, since they are supposed to be similarly powerful.

Short answer: you can do that. If it doesn't have the shapechanger flag/ability/whatever, then yes, that will work to permanently make them a human, forever. Bonus if they're willing, as you don't even need to fudge a save or anything.

[Mr Adventurer]

As well, the creature retains its personality and alignment - so it'd presumably still become a person with haglike motivations and behaviour.

[Eriol]

As well, the creature retains its personality and alignment - so it'd presumably still become a person with haglike motivations and behaviour.
I both agree with you and don't here. From the text of the spell:

The target’s game statistics, including mental ability scores, are replaced by the statistics of the new form. It retains its alignment and personality.
Mental ability scores are affected, so that can change aspects of its personality, though overall they should be the "same idea". A Hag's "nature" can be affecting how aggressive (or whatever) it is, so that would be changed, even if it's "nurture" aspects (how it was raised) are retained. Similar themes exist in the other direction when people become Vampires, infected by Lycanthropy, or other things that don't explicitly affect their mental state (like possession) but very much affect their "nature" and thus cause them to act differently.

I would say this is all well within the realm of "DM Fiat" however on how much/little this has an effect on any one particular NPC. If this was affecting a PC, then it would be very much a discussion between the player and the DM.

[Specter]

Seems to me like Wish could be better than True Polymorph in this case.

[Mr Adventurer]

I both agree with you and don't here. From the text of the spell:

Mental ability scores are affected, so that can change aspects of its personality, though overall they should be the "same idea". A Hag's "nature" can be affecting how aggressive (or whatever) it is, so that would be changed, even if it's "nurture" aspects (how it was raised) are retained. Similar themes exist in the other direction when people become Vampires, infected by Lycanthropy, or other things that don't explicitly affect their mental state (like possession) but very much affect their "nature" and thus cause them to act differently.

I would say this is all well within the realm of "DM Fiat" however on how much/little this has an effect on any one particular NPC. If this was affecting a PC, then it would be very much a discussion between the player and the DM.

Mmm. I agree with what you're saying to an extent, but "retains its alignment and personality" is pretty cut-and-dried, the way it's presented. And... can't True Polymorph still be Dispelled? Possibly not actually, since as I read it, you concentrate for the duration, then the spell ends, but the change persists anyway.

Rereading the spell, this could actually be a great way of getting rid of things: evil artefact, someone you don't like you've Polymorphed into a necklace, soul gem of a demon lord, lich phylactery, whatever. Equip it on a creature, polymorph that creature, and it's absorbed. Then concentrate so the transformation is permanent. Eventually whatever other creature you Polymorphed the second target into dies and decomposes naturally. No targets left to retrieve the original item.

[Iampower]

Thanks for the replies. I already know what i intend to do . I just wanted some assurance that it was, at least technically, within the rules.
Wish would probably be better but true polymoroh has more story potential since it can be dispelled. Were nearing the end so im hoping they dont change their mind and use wish instead.
If this work out and we start a second campaign i plan on using the child as the "party's sorcerer friend" npc.