Can I play two Stupefies in a row when my opponent attacks and passes priority, or does the first Stupefy resolving cause priority to pass and move to damage calculation?

Ruling: You can play multiple Stupefies (or other Reactions) in a row without passing priority. You can chain Actions and Reactions together before passing priority.

Sequence:

• Opponent moves unit to battlefield and passes priority
• You gain Focus and play first Stupefy
• You can immediately play second Stupefy without passing priority
• After you pass priority, opponent gets priority again
• Priority must be passed by both players consecutively to move to damage calculation

Nuances:

• You can chain Actions and Reactions in sequence (e.g., Action, React, React) before passing priority
• The resolution of a card does not automatically pass priority - priority is only passed when a player explicitly passes or by the rules