Thundermaw Hellkite

Text:

Flying
Haste (This creature can attack and as soon as it comes under your control.)
When Thundermaw Hellkite enters the battlefield, it deals 1 damage to each creature with flying your opponents control. Tap those creatures.

Rulings:

• 11/17/2017 Thundermaw Hellkite will deal 1 damage to each creature with flying your opponents control whether those creatures are tapped or untapped.
• 11/17/2017 If the damage that would be dealt to a creature with flying is prevented, that creature will still be tapped. If that damage is redirected to another creature, the creature with flying will be tapped, not necessarily the creature that ultimately was dealt damage.