Can you play Ride the Wind (an action spell) in response to an opponent's Fox Fire spell to remove a unit from the battlefield and cancel the spell?

Ruling: No, you cannot play Ride the Wind in response to Fox Fire. Action spells cannot be added to an existing chain - they can only start a chain. When an opponent casts a spell, they start a chain, and you can only respond with reaction spells, not action spells.

Sequence:

• Opponent casts Fox Fire, starting a chain
• You may respond with a reaction spell (like Discipline)
• Your reaction spell resolves first
• Fox Fire resolves second
• After the chain fully resolves, you get an opportunity to play action spells in the open game state

Nuances:

• Actions can only be played in open game states (when no chain exists)
• You cannot play an action to counter an action, only a reaction can respond to spells in a chain
• Reaction spells can also start chains, and can only be responded to with other reactions
• Some spells trigger showdowns (those that move units into battlefields) while others do not (damage/stat modification spells)