If Tasty Faefolk dies at a battlefield with Zhonya's hidden, can you flip Zhonya's in reaction to the Deathknell trigger to save the Zhonya's proc?

Ruling: You can flip Zhonya's in response to Deathknell, but this only saves the Zhonya's proc (prevents it from being trashed) - it does not save the Faefolk itself, which is already dead. Whether this works depends on if the battlefield is contested.

Sequence:

• If Faefolk dies during combat (contested battlefield): Deathknell triggers, you still have control of the battlefield during the chain, you can flip Zhonya's in response to save the proc
• If Faefolk dies outside combat (not contested): You immediately lose control of the battlefield when Faefolk dies, Zhonya's is trashed before you can react to Deathknell

Nuances:

• The key factor is whether the battlefield is contested, not whether death was caused by combat damage vs ability
• If Faefolk dies by ability mid-showdown (while contested), you can still save Zhonya's because control is locked until contested is removed
• Control is locked during combat until the contested state is cleared, even if you have no units remaining
• Flipping Zhonya's before Faefolk dies would save the unit but prevent the Deathknell trigger entirely