When the last unit of a showdown dies, are you still in the showdown? Can the other player cast an action afterwards?

Ruling: Yes, you are still in the showdown when the last unit dies. The other player can cast an action afterwards.

Sequence:

• An action is cast that kills the last unit
• The showdown continues
• The other player can cast an action in response
• The showdown only ends when all players have passed focus