Does a defending unit with Shield (like Stalwart Poro) retain the Shield buff when targeted by Challenge during a showdown?

Ruling: Yes, the Stalwart Poro keeps the Shield buff when challenged during a showdown because it is still considered a defender.

Nuances:

• Challenge simply causes units to deal their might values as damage to each other
• The defender status from the showdown persists even when Challenge targets that unit
• Shield applies based on defender status, not specifically to showdown combat