When Fiora triggers at end of turn after a unit regains Mighty during the expiration step, can players respond with effects like Stupefy before the next expiration step?

Ruling: Yes, when Fiora triggers after a unit regains Mighty during the expiration step, the trigger goes on the chain and players can respond to it before proceeding to the next phase. Any effects played in response (like Stupefy) will not be cleansed until the next end of turn.

Sequence:

• Expiration step begins removing "this turn" effects
• Unit regains Mighty, triggering Fiora
• Procedures pause before completing the expiration step
• Fiora's trigger goes on the chain
• Players can respond to the trigger
• Any new "this turn" effects played now won't expire until the next end of turn

Nuances:

• This follows the same logic as combat damage deathknell triggers
• Similar to temporary units dying and being responded to with other temporary units
• The development team is aware of this interaction and may adjust the sequence in a future update