Hi!
Just to see if I understood the Elemental Mastery move right: if I'm the druid and the party is closed in a long distance arrow-fight with a horde of goblins inside a huge underground cave, I could call the spirits of the earth to shake the cave and make it crumble onto the goblins, thus ending the fight with just that move, right?
If that's the case, I like the that you can only have choose two of the three options, it makes the move powerful, but with consequences. I agree that they should probably be baked inside the move in some way, but that's just a wording-thing.
Then, a little clarification on the Shapeshifting move: how would a pc use a monster (animal, in this case) move? Basically, the monster moves are there to use when a pc fails a roll, so they can just be a description of what happens, but a pc should always roll anyway? It shouldn't be allowed to "rend an enemy apart" (monster move invented on the spot) without rolling, right? If that's the case, how would a pc use "rend an enemy apart"?