If a defender reacts to a Deathknell effect by revealing a hidden unit, but the Deathknell doesn't kill all attackers, what happens next?

Ruling: A new combat showdown will be staged with the same role assignments (the revealed unit remains as a defender against the surviving attackers).

Sequence:

• Deathknell effect triggers when defending
• Defender reacts by revealing hidden unit
• Deathknell resolves
• If attackers survive, a new combat showdown occurs with the same roles