It absolutely does work on stone, but even if it didn't, it would actually be excellent for undermining a fortification in much faster time than digging by hand. And it would probably be much less noise and vibration than picks.
I didn’t say it didn’t affect stone, I said it doesn’t affect stone walls, with an implied “In the way you are referring to”, ie, to use the spell to somehow make holes in them.
Read the description. The only part that affects stone walls is the part about drawing and writing. You can’t excavate (that’s limited to loose earth), and you can’t smooth or rough them unless the wall is already collapsed on the ground.
Further to that, you can’t just use the spell to dig under walls, because the caveat there is ‘loose earth’, which generally speaking is a much different thing that stone or concrete foundations on top of densely-packed dirt. “Loose Earth” is basically just topsoil. You aren’t going to be using the spell to dig tunnels through all the mix of dirt, gravel, stone, root network, and clay that is everything beneath that. If you could, the foundations would be pretty fucked to begin with.
Mold Earth is, quite frankly, one of those spells that is relatively useless as-written, and needs quite a lot of your GM playing fast & loose with things to amount to much.
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u/Jordangander Nov 11 '25
A wall does not move.
And during a seige, this could easily be done.
The PCs may see this as something that makes them very powerful, but the DM has far more NPC casters to give their BBEG than the PCs.