Power Word Kill and Wildshape

[shomaxt]

How does Power Word Kill work when used on a Druid Wildshaping as another creature? Does it just kill the Druid entirely, or does the animal shape that the Druid simply die and revert the Druid back to their base form at the Hit Points they had before they transformed?

[Lokiare]

How does Power Word Kill work when used on a Druid Wildshaping as another creature? Does it just kill the Druid entirely, or does the animal shape that the Druid simply die and revert the Druid back to their base form at the Hit Points they had before they transformed?

They die irrevocably.