How flexible is the movement of loose earth via the Mold Earth cantrip

cantripsdnd-5e

Published on page 162 of Xanathar's Guide to Everything, the first bullet point of Mold Earth states:

"If you target an area of loose earth, you can instantaneously excavate it, move it along the ground, and deposit it up to 5 feet away. This movement doesn't involve enough force to cause damage."

Emphasis mine.

I notice that the Shape Water (XGE pg. 164) and Control Flames (XGE pg. 152) cantrips both have explicit wording that clarifies that, with a single casting, not only can the total movement of either element be no greater than 5 feet but also that this movement can only be in a single direction.

In contrast, the text of Mold Earth seems to lack both of these important clarifications. Instead, for the purposes of a single casting, it gives no limitation on the total movement or vectors allowed, and only limits how far the loose earth can ever get from the area it was taken from. Therefore…

Firstly:

Instantaneously, could a caster use a single casting to excavate a cube of loose earth into a square adjacent to the source point, then have the cube continue a path along the ground that deposits it into a different square that is likewise adjacent to the source point?

This first question addresses loose earth that instantaneously takes a path along the ground which covers more than 5 feet of movement in multiple directions, but without ever disobeying the singular limitation provided of "up to 5 feet away".

For an ingame example, this asks whether or not a caster could use a single casting of the cantrip to move a volume of earth to the opposite side of a wall that was 5 feet in length and height, as long as both the path and destination were visible and always kept within adjacent squares.

Secondly:

If the above is possible, could a caster use a single casting to perform the above, but instead have the loose earth be ultimately deposited into the same square it was excavated from?

This second question addresses that, to my understanding, depositing something "up to 5 feet away" includes the possibility of this deposit being "0 feet away".

In both examples, instantaneous excavation and movement of loose earth has been conducted along the ground, with both instances having more than 5 feet of total movement, but never once being moved or deposited more than 5 feet away.

RAI is helpful, but I would like replies to primarily focus on the RAW interpretation, please.

Best Answer

There are no hidden limitations on the movement

I will put highlights on the text of Mold Earth I think are relevant to answer your questions:

You choose a portion of dirt or stone that you can see within range and that fits within a 5-foot cube. You manipulate it in one of the following ways:

If you target an area of loose earth, you can instantaneously excavate it, move it along the ground, and deposit it up to 5 feet away. This movement doesn't involve enough force to cause damage.

For your questions:

"Up to 5 feet away" refers to the location of the excavation. The spell does not say the movement needs to be in a straight line. If one side of the dirt or stone that you want to move was blocked by a short wall section that you want to move it around, this would be possible but only if you can see the other side, as you must be able to see dirt or stone you move. If the wall was long enough to block all paths within five feet, it would not work, as the earth is moving along the ground, not teleported.
It may be debatable if 0 feet away still counts as away, and if effectively leaving the earth in place counts as excavating it, ask your DM. I think the answer is likely no. It even is questionable if you could put back the earth in two castings, as you only can excavate earth, and moving a mound of earth is not excavating it: the dictionary definition of excavate is to dig a hole or channel in the ground. The "up to" in the distance is not the only part of the text that is relevant to understand what the spell is meant to do.

Background

In general the rule for spells is that they only do what they say, nothing more. At the same time, there are no hidden rules, so if the spell says it can do something, and imposes no restrictions on it, then it can do that thing without restriction if there is no general rule against it. But to consider what the spell says, you need to look at the entire text, not only at a part of it.

For interpreting the text, unless you are dealing with a specific game term defined in the rules, words are expected to have their plain English meaning. Lastly, 5e is a game of rulings, so it is common practice to have borderline cases adjudicated by the DM to keep the rules text from becoming unwieldy.

Not as much protection as you'd think.

Try this at home - get a shovel, and try to pile "loose earth" into the shape you've described (3ft tall, 2ft deep wall). It will immediately fall down into a pile. The angle of repose of soil is 30-45 degrees. In your configuration (2ft diameter base) the pile needs to have an angle of repose of 75 degrees. So the entire thing flops over to about half its height. The soil from the sides of the hole is also falling inwards, filling up your hole, probably reducing the amount of cover from the hole by half as well. If you're unlucky, the soil from the wall will fall backwards into your hole and reduce the depth even further. It would look more like this:

|      OO

|   OOOOOOO

XXXXXXXXXXXO      XXXXXXXXXX

XXXXXXXXXXXOOO XXXXXXXXXXXXX

XXXXXXXXXXXXOXXXXXXXXXXXXXXX

If you're lucky, you'll get 3 feet of cover (partial cover) out of this. There's a reason soldiers build trenches out of packed, not loose, soil.

[RPG] Does using Mold Earth to trip someone break its rule against causing damage

Well done!

Congratulations to your player in coming up with an imaginative use for the spell. Congratulations to you for enabling it and working out simple, practical mechanics for it.

I personally would have made it a Dexterity (Acrobatics) ability check rather than a saving throw as it is an attempt to keep your balance rather then actually resist the spell and also because more creatures have proficiency in Acrobatics than Dexterity saving throws. I would also consider Strength (Athletics) to stand your ground and give the target the choice.

I would also rule that creatures with other than 2 legs get advantage due to their greater stability.

Is this OP?

Does it break the rule about causing damage? Clearly not.

However, what I think you are asking is: is this overpowered for a cantrip?

My take is probably not and here's why:

The wizard is giving up their action to possibly knock a single enemy prone. This means they are not using that action for something else like casting a higher level spell or a different cantrip. The chance is 70% for a modifier of 0 on the roll (going down by 5% for each +1).
If the wizard instead used their action to Help they would guarantee advantage for one of their companions.
"Fool me once shame on you, fool me twice shame on me". Guess who the creature is targeting next round, you know, while the wizard is concentrating on the Mold Earth cantrip? With a ready action, the caster is concentrating on the spell from their turn up to the trigger point.
Anyone with a decent Strength (Athletics) modifier can do this as one of their attacks in an Attack action. If they have the same modifier they are better than the wizard (77.25%) and they are even better as the opponent's modifier increases. If they have multiple attacks, they can do this and still attack themselves.
Don't even get me started on someone with expertise in Strength (Athletics) and the Shield Master feat. Grapple, knock prone with a bonus and they can't get up because their movement is 0.

Deeper concerns

Readying action requires you to "decide what perceivable circumstance will trigger your reaction." That is perceivable to the character. "When it completes its turn" is perceivable to the player, not the character.

I'm not saying it can't be done, I'm just saying it can't be done with that trigger.

"When it attacks, moves or casts a spell" is a workable trigger but there is the possibility that it does none of those things and the wizard is left with nothing to hang their action on.