When Purple MF is at the base and Blitz is played into an uncontrolled battlefield, how many showdowns occur?

Ruling: Two showdowns occur - first an open showdown, then a combat showdown.

Sequence:

• Blitz is played to an empty battlefield, staging an open showdown
• Blitz's ability triggers and goes on the chain
• Purple MF's ability moves an enemy unit to contest the battlefield, staging combat
• Blitz's ability resolves during cleanup step 8
• At cleanup step 9, the staged open showdown starts (because showdowns only start after the chain is empty)
• After the open showdown resolves, the staged combat showdown begins

Nuances:

• This creates opportunities for removal before units gain might from combat
• Matters for cards with Assault and Shield keywords
• There may be a missing cleanup step in the current rules that would clear the staged open showdown once the battlefield becomes contested