If you use Wind Wall to block Bullet Time, does Wind Wall happen before or after the player using Bullet Time has chosen how much power they intend to use?

Ruling: Wind Wall happens before the Bullet Time player chooses how much power to pay. The player using Bullet Time pays no extra power because the amount is chosen during resolution, not when the card is played.

Sequence:

• Bullet Time is played and put on the chain (paying only its base cost and declaring the battlefield as target)
• Opponent can respond with Wind Wall or other reactions
• If no responses, Bullet Time resolves
• During resolution, the Bullet Time player chooses and pays any amount of power
• Bullet Time's effect fully resolves
• Opponent can then play cards after full resolution

Nuances:

• The power payment is part of Bullet Time's effect, not an additional cost
• Opponents cannot respond during resolution (including after seeing how much power is paid)
• The target of Bullet Time is the battlefield, declared when played