How does Investiture of Stone interact with Meld into Stone?

Question

While this is primarily a druid spell combination, the Arcana Cleric, Divine Soul Sorcerer, and Genie Warlock subclasses all have access to both spells as well.

The 3rd-level spell Meld into Stone allows you to remain inside of stone for a lengthy duration of eight hours, does not require concentration, and (emphasis mine):

You step into a stone object or surface large enough to fully contain your body, melding yourself and all the equipment you carry with the stone for the duration...

You remain aware of the passage of time and can cast spells on yourself while merged in the stone. You can use your movement to leave the stone where you entered it, which ends the spell. You otherwise can't move.

Minor physical damage to the stone doesn't harm you, but its partial destruction or a change in its shape (to the extent that you no longer fit within it) expels you and deals 6d6 bludgeoning damage to you. The stone's complete destruction (or transmutation into a different substance) expels you and deals 50 bludgeoning damage to you. If expelled, you fall prone in an unoccupied space closest to where you first entered (PHB, pg 259).

Whereas the 6th-level spell Investiture of Stone lasts for up to ten minutes, requires concentration, and gives the following benefit (among others) until the spell ends:

You can move through solid earth or stone as if it was air and without destabilizing it, but you can't end your movement there. If you do so, you are ejected to the nearest unoccupied space, this spell ends, and you are stunned until the end of your next turn (XGE, pg 159).

The spell mentions that your movement does not destabilize the stone nor does it actually transmute it to air, which neatly skirts the terminating conditions of Meld into Stone. So it doesn't seem as if merely moving through stone would expel you and cause you to take the accompanying damage.

So far so good. However, Investiture of Stone states that you cannot end your movement within the stone without being ejected to the nearest unoccupied space and stunned, while Meld into Stone is also explicit in describing that if expelled from the stone you fall prone in an unoccupied space closest to where you first entered.

Let alone trying to decide whether you can remain within the stone, the effects of the two spells are conflicting and determining which would take precedence is unclear.

The crux of the issue, as I see it, is that Meld into Stone allows you to remain within stone at the cost of your movement, while Investiture of Stone allows you to move through stone but not remain within.

While it does not seem as though these spells were intended to be used in conjunction with each other, Investiture of Stone has a range of self and as such is one of the few spells you are allowed to cast while under the effects of Meld into Stone.

How would you reconcile the combined use of these seemingly contradictory spells? Please include how to resolve the effects in event of expulsion from the stone (i.e. fall prone, get stunned, and/or take damage).

Side note: since casting spells on yourself is listed as an acceptable action during Meld into Stone, I've gone ahead and assumed that casing Investiture of Stone is permissible regardless of its verbal and somatic components. By all means feel free to address this point if you disagree, but if so please assume the Subtle Spell Metamagic is being used in this scenario as that isn't the purpose of the question.

Answer 1

I likewise believe territories like this are 100% a DM call, so consider the following simply some creative suggestion.

As a DM trying to create a world my players enjoy, I would bend the rules in a functional blend of the two spells and effectively grant an ability that already exists in RAW. Earth Elemental has:

Earth Glide. The elemental can burrow through nonmagical, unworked earth and stone. While doing so, the elemental doesn't disturb the material it moves through.

To be more clear, I would rule the player can freely move in and out of stone while both effects are active, and may end his or her movement there. Considering a player must expend two spell slots, use two turns, and maintain concentration throughout, the effect is not unreasonable to me. Counterexamples are welcome, but I don't believe it exceeds what is possible with other spells or effects of a greater level or cost.

As for the finer interactions:

• It's reasonable to think Meld Into Stone ejects you to the nearest space simply because you can't move after you enter the stone. I would use Investiture's rule and eject the player into the nearest space from their current position in all applicable cases.
• If the stone space the player occupied was transmuted, damaged, or destroyed, Meld ends and its bludgeoning damage applies. The player was part of the stone, after all. I don't see a reason this should end Investiture, apart from the concentration check
• If concentration on Investiture ends, I see two possibilities- eject and be stunned, and both spells end; Or (hehe) the player is frozen in stone since they've lost the effect that was allowing them to move, but retain the effect that makes them part of the stone. They remain so until Meld ends. I might be nice and let them use movement to leave if they just happen to have frozen at the edge of the stone surface (i.e. in a space they could have occupied by casting only Meld).
• I would allow Meld to remain active as long as concentration is maintained on Investiture, even if the user leaves the stone area. This is absolutely homebrewery, but I feel it's justified based on the cost and risk of the combo.

Answer 2

You can certainly cast them together, but it won't be very useful.

My guess is that you're looking for a way to use both together to travel though stone for (relatively) long distances. Unfortunately, this won't work.

A couple key points on Meld Into Stone

You step into a stone object or surface large enough to fully contain your body, melding yourself and all the equipment you carry with the stone for the duration.

You can use your movement to leave the stone where you entered it, which ends the spell.

You otherwise can’t move.

The first part clearly indicates that you enter the stone from outside, since you enter an object (a single discrete piece of stone, like a statue or boulder) or a surface (a part of a larger stone structure, or a cliff face perhaps).

The second part states that we must leave the stone where we entered it when the spell ends, and since we already determined in the last point that we had to start outside the stone, we return to being outside the stone when we leave, at the same place we entered it. And once we leave the stone, the spell ends.

The last section simply states that movement while the spell is active, we can't use this to enter a cliff face at on point and move to another point on the cliff face, for example, or merge with a castle wall, then move around to the other side of the castle.

And a key point on Investiture of Stone

You can move through solid earth or stone as if it was air and without destabilizing it, but you can’t end your movement there. If you do so, you are ejected to the nearest unoccupied space, this spell ends, and you are stunned until the end of your next turn.

If you have both active at once (cast Meld Into Stone, then cast Investiture of Stone while inside the stone), Investiture of Stone won't allow you to move through the stone object or surface, since even though Investiture of Stone allows us to walk through stone, Meld Into Stone specifically forbids us from doing any movement, except to leave the stone. In Medix2's answer they argue that neither is more specific and that a DM would have to rule which takes precedence, but the two effects aren't contradictory. Investiture of Stone allows you to move through stone, but Meld Into Stone prevents you from moving in any manner, regardless of how you move. And even if you could move, if you're inside stone at the end of your turn, you are ejected, stunned, and both spells end, since ending your turn inside stone ends Investiture of Stone automatically, and leaving the stone ends Meld Into Stone.

In the reverse situation, where Investiture of Stone is active, and then you cast Meld Into Stone to enter a stone surface, you would still be ejected at the end of your turn because Investiture of Stone doesn't make an exception for if you enter the stone via other means.

Answer 3

Neither spell is more specific than the other; a GM has to make a ruling

In particular here are what I would call the most conflicting bits from the spells. The investiture of stone spell states (emphasis mine):

[...] You can move through solid earth or stone as if it was air and without destabilizing it, but you can't end your movement there. [...]

Meanwhile, meld into stone states (emphasis mine):

[...] You can use your movement to leave the stone where you entered it, which ends the spell. You otherwise can't move. [...]

These are completely opposed and there is no clear way of resolving that, so the GM will have to make a ruling. So a GM is going to have to make a ruling about whether you can even move in the first place, and then, of course, also rule about how you can move while under the effects of both spells.

That said RevenantBacon makes an excellent argument about how the spells interact. I greatly suggest reading its take on the specificity of the spells. In full honesty, I like that answer better than my own