Flight

You gain controlled Flight up to your speed. If you take damage while flying higher than 5ft above the ground, your altitude drops by 20ft. If this would reduce your altitude to the point where you touch the ground, you become rooted and cannot fly again until the end of your next turn. If the attack that reduced your HP came from a flying creature other than yourself, you do not lose altitude.

When you end your turn within 5ft of the ground, Flight ends.