Can you use Hidden Blade on your own unit after assigning combat damage but before damage resolves, then use Sett Legend to recall the unit and still deal damage?

Ruling: No, you cannot assign damage and then use Hidden Blade. Hidden Blade must be played from the facedown zone before reaching the combat damage step, when you have priority.

Sequence:

• You must play Hidden Blade when you have priority before the combat damage step
• If both players pass with focus on an empty chain, you proceed to combat damage
• Once you're assigning damage to each other, it's too late to play Hidden Blade

Nuances:

• If you use Hidden Blade when you have priority, you kill your own unit and draw 2 cards, but then deal 0 combat damage
• If you pass/pass and deal combat damage, all units die and Hidden Blade goes to the trash since you've lost control over the battlefield