Flight

You can Fly through the air as if you were moving on land and your movement speed is doubled while doing so.

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 an flying creature other than yourself, you do not lose altitude.