Seems to me one really obvious way to use this is a variety of sandstorm...  It need not cause damage to blind an enemy or prevent missile fire.

You can hav a fighter disarm someone then bury the weapon

Can I use mold earth to create shapes, colours and patterns to potentially hypnotise/ put someone in a trance? Or simply dazzle them for a couple seconds? I'm thinking like swirling patterns were used to hypnotise people so could I with this?

If i wanted to destroy a wall made from mold earth, how much "health" would it have to be destroyed?

I had a Xorn that had eaten a gnome rouge of mine.
The wizard used this spell to open the xorn and let the little guy out.
I couldn't believe it, but based on what I know, the spell would totally work on elemental stone!

Quote from Chaoko954 >>

I had a Xorn that had eaten a gnome rouge of mine.
The wizard used this spell to open the xorn and let the little guy out.
I couldn't believe it, but based on what I know, the spell would totally work on elemental stone!

 It wouldn't. The excavation only applies to loose earth (i.e. dirt) a living creature made of stone certainly not qualify.

Also this spell cannot cause any damage. Openly up a creature would arguably cause that.

As far as the viability of using mold earth to create a massive wall or, even worse, a castle I would say it doesn't. Mold earth's excavation feature can only be used on loose earth (i.e. surface level dirt). Anyone who has ever done any digging at all can tell you that after 2ish feet (often times less) dirt becomes hard packed to the point where the spell would not apply. Creating a wall is generally unfeasible because 1. your really only excavating about 2 feet deep with a single use and 2. the loose earth is still loose after it's been excavated. Unless you use some method of hardening earth to become load bearing it's not going to become a very great wall, let alone a castle because it is still, in fact, loose earth-- someone could just as easily push through it or push it over. 

This spell is super useful in a RP sense: digging graves, digging holes to place traps/ranger graves, creating dirt slopes to run up walls, etc... Using it to create Leomund's Tiny Hut or an instant  fortress is not one of those uses.

Step 1: Create a 5ft hole

Step 2: Apply Grease to 10ft area

Step 3: ???

Step 4: Create Bonfire once 5ft hole is occupied. (Marshmallows are not needed but encouraged.) 

Step 5: Profit!!!

Quote from ZagrothCralxan >>

If i wanted to destroy a wall made from mold earth, how much "health" would it have to be destroyed?

 I would have it be 1 HP/1ft of dirt, so 5 HP. However, if someone was using it as a shield or half-cover to hide behind any damage over the 5HP they would take as collateral damage. (This is only if the mold earth wall is targeted, otherwise half-cover still applies to the person behind it.)

So I think it was suggested that you couldn't bury an enemy with this spell, at least not without two casters. But I am thinking that other than making a wall, I want to use this to bury myself! Ground beneath me moves out then moves back over me. Since I control the earth, I figure that I can make a hole to the surface for breathing (curved to disallow arrows) and a cavern for my hands to then get me out. Thus I instantly disappear. Perhaps I send my hamster up the hole to check if the coast is clear before I pop back out.

Could you use this well disengaging leaving a trail of difficult terrain in your wake?

No. The final rider of the spell is that you can only create 2 non-instantaneous effects at a time.

The spell looks ideal to dig a few foxholes very quickly, maybe even in mid-combat.  It would is also be a decent way to fortify a camp, or make choke points, given enough time.  I like the idea of Greasing a slope made with this spell.

does it also affect metals?  Because in a geology class, the teacher kept calling metals a type of stone.  I was just wondering for some clarification.

Quote from KaiDallowHeadphones >>

does it also affect metals?  Because in a geology class, the teacher kept calling metals a type of stone.  I was just wondering for some clarification.

 I think that it wouldn't apply to refined metal but would apply to unrefined ore, since the ore is embedded in stone.

Totally got hosed by this spell. Druid cast it to get through my swamp chase which was a mechanic I created to be a series of checks to determine what the swamp terrain was like. I built it to be a max travel of 12 miles per day unless they want to roll exhaustion checks for each mile above the 12 miles. Their destination was 24 miles away. Roll of 8-20 gets you no encounters or ability checks and you move 4 miles of the 12 for the day (without exhaustion checks kicking in). Roll a 1-7 and something impedes your travel and you move only 2 miles. Either a fairly easy encounter happens or they have to roll athletics, acrobatics, or nature checks and need two consecutive saves to make it to the next 4 mile check. Each fail is 1d6 damage for skill check fails. For each stretch of 1-7 rolls, it reduces the total miles in a day to be traveled without exhaustion by 2. This was built for a one-shot that was going to be less combat heavy and to introduce exhaustion mechanics.

The druid ended up casting this constantly to create a smooth regular terrain trail where they could move the full 24 miles in the day. I can't see anyway around that. So I just rolled on a table for one day to determine if an encounter happens and they got the big swamp monster that I had chasing them get them to fill the time. It ended in a TPK for them.

Can you mold earth a earth element

If the caster had surprise on the target and a higher initiative, they would get two actions before the target. This would allow one caster to cast the cantrip and fill in the hole the next action.

Quote from vishun >>

Totally got hosed by this spell. Druid cast it to get through my swamp chase which was a mechanic I created to be a series of checks to determine what the swamp terrain was like. I built it to be a max travel of 12 miles per day unless they want to roll exhaustion checks for each mile above the 12 miles. Their destination was 24 miles away. Roll of 8-20 gets you no encounters or ability checks and you move 4 miles of the 12 for the day (without exhaustion checks kicking in). Roll a 1-7 and something impedes your travel and you move only 2 miles. Either a fairly easy encounter happens or they have to roll athletics, acrobatics, or nature checks and need two consecutive saves to make it to the next 4 mile check. Each fail is 1d6 damage for skill check fails. For each stretch of 1-7 rolls, it reduces the total miles in a day to be traveled without exhaustion by 2. This was built for a one-shot that was going to be less combat heavy and to introduce exhaustion mechanics.

The druid ended up casting this constantly to create a smooth regular terrain trail where they could move the full 24 miles in the day. I can't see anyway around that. So I just rolled on a table for one day to determine if an encounter happens and they got the big swamp monster that I had chasing them get them to fill the time. It ended in a TPK for them.

 They wouldnt be able to do it. Not enough time to cast it that much. 1Miles=5280 feet. Divided by 5 foot cube=1056 times to cast mold earth. Multiply by 6 seconds per casting and divide by 360 to convert to hours.  17.6 Hours of nothing but casting mold earth to convert a single mile of swamp. 

I tried casting this on a gargoyle to make either its eyes seal shut or a stone blind fold appear on its face the dm ruled no.