@JeremyECrawford A flying creature takes a op. attack from a guy with Sentinel feat.

As its movement became zero, it falls, right?

— ɟןǝsɯıɥ‾oɹbo@🎮 (@ogro_himself) October 6, 2016

If your speed drops to 0 while you're flying, you fall if you're not hovering. See the PH, p. 191, for more details. #DnD https://t.co/5LqmT59pef

— Jeremy Crawford (@JeremyECrawford) October 6, 2016