Cunning Action: Aim contains the following:
You can use this bonus action only if you haven't moved during this turn, and after you use the bonus action, your speed is 0 until the end of the current turn.
Would a rogue under the effect of the fly spell be able to use this feature while in the air? If so, would he fall to the ground after using it? Does something change if they naturally have a fly speed and it isn't from the fly spell?
Best Answer
They would not fall, but flying speed would be reduced to 0
The Fly spell reads:
Since flying speed is a speed, This means that when speed is reduced to 0, flying speed is also reduced to 0. The rules on flying speeds being reduced to 0 read:
(emphasis mine)
The flying rules say that when flying speed is reduced to 0 the flying creature falls. However, since these rules essentially say that if the flying status is created by magic, with the fly spell as an example, in this case the character would not fall, so they would simply be unable to move after using the cunning action during this turn.