To control your mage hand, you use your action. Otherwise, the hand does nothing. For more on how that magical hand does its wondrous business, check out page 256 in the “Player’s Handbook.” If a conjured hand is floating in the air making a stop hand signal, and I run into it, does the hand phase through me, get moved, or physically stop me? What constitutes "doing nothing" in this case? Are conjurations movable by mundane means, or are they anchored in place?
— Thomas "You Can Call Me Tom" (@thomasabarry1) January 15, 2019
There are no general rules for conjurations or for any other school of magic. A spell's description tells you what the spell does.
Mage hand creates a spectral hand that is neither an object nor a creature, and this ghostly appendage isn't said to occupy any space. #DnD https://t.co/iHoGlqCrJ7
— Jeremy Crawford (@JeremyECrawford) January 15, 2019
but does the hand move along with the planets rotation, or would it slowly drift towards the next timezone as the planet rotates underneath it?! 😂😂😂
— Eric Gerson (@ETGers) January 15, 2019
The rules of D&D don't account for planetary rotation. 🌍
If such things are a concern at your table, DM, I leave them in your capable hands. #DnD https://t.co/84hyerbFqc
— Jeremy Crawford (@JeremyECrawford) January 15, 2019
So there's no rules pertaining to what happens when a Mage Hand hits a moving object? No rules pertaining to whether a creature can lift and throw a Flaming Sphere as opposed to the sphere blocking movement?
— Thomas "You Can Call Me Tom" (@thomasabarry1) January 15, 2019
The general rules for spellcasting are in chapter 10 of the "Player's Handbook."
The rules for a specific spell are in that spell's text.
Anything beyond those rules is up to your imagination and your DM's adjudication. #DnD https://t.co/OeGnwmx3Qu
— Jeremy Crawford (@JeremyECrawford) January 15, 2019
Well that's kind of my point. Are things that are not objects nor creatures locked in space, or do they function like any other piece of matter? But it sounds like the answer is "ask your DM."
— Thomas "You Can Call Me Tom" (@thomasabarry1) January 15, 2019
If a spell creates an energy/force/ghostly thingy that isn't an object or a creature, the spell tells you how it works. The magic of the spell determines how the magical thingy operates in the world. #DnD https://t.co/OmRQQFJTe1
— Jeremy Crawford (@JeremyECrawford) January 15, 2019
Worry not. Jeremy has said multiple times that rules with a lot of corner cases test poorly; all of the little details start to distract from the main functionality. The DM’s there for the weird situations. That's exactly right. The rules deal with the common cases. DMs handle the rare cases.
— Jeremy Crawford (@JeremyECrawford) January 16, 2019