If I move into an occupied battlefield and play Hidden Blade (killing their unit), can my opponent still play their Hidden Blade from hand even though their unit is now dead?

Ruling: Yes, the opponent can still play Hidden Blade from hand after their unit dies. The showdown doesn't close until both players pass in succession, regardless of how many units either player has remaining on the battlefield.

Sequence:

• Attacker moves into occupied battlefield and plays Hidden Blade with priority, then passes
• Defender cannot respond before Hidden Blade resolves (it's action speed from hand), so they pass
• Hidden Blade resolves, killing defender's unit
• Priority passes to defender who can now play Hidden Blade from hand
• Both players continue passing priority until consecutive passes occur

Nuances:

• A battlefield with no units but hidden cards in hand is a valid game state during showdown
• The showdown only ends when both players pass consecutively, not when units are eliminated