If it is a controlled mount I would think that would dismount while the mount is stopped. Given the way movement works in 5E that will always be that way technically at the start of the turn.
I was simply responding to the example as given by Lanefan, where he hoped for a target that was moving at considerable speed--specifically with the intent of harming the rider when they dismounted.
Here are some creative attempts I've seen in play:
Daydream - to stop concentration
Surrender - used against a leader during a standoff/negotiation after she asked for the party to surrender
Swim - got an enemy to jump in a moat taking him essentially out of the fight
Lie - This was used interrogating a prisoner to make an enemy being interrogated lie, thereby knowing the truth. (failed due to a save)
Breathe - Attempted to force a Dragon to use his breath weapon in a location near no allies (failed due to save .... but he breathed anyway)
Regurgitate - attempted to be used to make a purple worm throw up a party member. Failed because of the language requirement (failed)
Okay! Some of these are much better. "Surrender" still seems to me pretty verboten, since the spell only works for
six seconds. "Lie" is more than a bit risky. Just because someone tells a lie, doesn't mean the exact opposite of what they said is true, unless you have
very carefully worded your questions--creative, perhaps, but not nearly as useful as you might think. "Breathe" is too non-specific; unless the dragon literally can't reach anyone, that could instead draw the breath to you (since, per the rules, movement can be freely blended with actions).
And that last one already would have failed anyway, so...not really a useful example of a better command?
So I'll grant Daydream as a clearly useful thing to do, and Lie as a risky but potentially useful thing. The others either don't work (Surrender/Regurgitate) or are much too specific (Swim/Breathe). Which...again, is sort of the point I was making. People frequently see more creativity in the 5.0 wording than is actually there, because they ignore the "not harmful" limitation, or the language limitation, or expect
rather a lot out of
Even with Swim, for example, I could
easily see a 5.0 DM saying, "He attempts to start swimming, but since he isn't in water right now, nothing happens." Which would be effectively equivalent to just telling the target to "wait." The caster assumed--and, IMO, the DM
very generously granted--that "Swim" would entail the additional idea, "
get to a place where you can swim". That's something that could easily result in a multi-minute back-and-forth between a DM and player because the player believes
command carries those extra implications and the DM doesn't.
