Can players start multiple chains during a Showdown, or does passing once forfeit the ability to start new chains?

Ruling: Players can start multiple chains during a Showdown. Both players must pass in a row without playing spells or activating abilities for the Showdown to close.

Sequence:

• Player A has Focus and Priority -> Plays spells/abilities -> Chain Resolves
• Player B gains Focus and Priority -> Plays spells/abilities -> Chain Resolves
• Player A gains Focus and Priority -> Passes
• Player B gains Focus and Priority -> Plays spells/abilities -> Chain Resolves
• (This can repeat any number of times)
• Player A gains Focus and Priority -> Passes
• Player B gains Focus and Priority -> Passes
• Showdown closes

Nuances:

• Passing once does not forfeit a player's ability to start a new chain later in the same Showdown
• The requirement is that all players must pass consecutively without any spells or abilities being played for the Showdown to close