When a unit moves to create a showdown, and the opponent responds by moving a unit to create a second showdown, which showdown resolves first?

Ruling: The showdown that began first resolves first. The second showdown becomes staged and will resolve after the first one completes.

Sequence:

• First showdown (at Reaver's Row in the example) resolves completely
• Second showdown (at The Arena's Greatest in the example) then resolves