Is a combat considered done if a unit is killed with a spell before dealing damage?

Ruling: No, the combat is not done. The combat showdown only closes when both players pass in a row while in an open showdown state (both passing instead of starting a chain while they have focus).

Sequence:

• Both players must pass consecutively during an open showdown state
• When the combat showdown closes, check if units controlled by different players are at the battlefield
• If no opposing units remain, the combat damage step is skipped
• The combat resolution step still occurs regardless

Nuances:

• Killing a unit with a spell before damage doesn't immediately end combat
• The combat damage step can be skipped, but combat resolution always happens