If I use Hextech Ray to deal 3 damage to a target in a showdown and pass priority, can my opponent use Ride the Wind to move the target and cause Hextech Ray to fizzle?

Ruling: Your opponent cannot use Ride the Wind to respond to Hextech Ray because Ride the Wind is an action card, not a reaction. Only reactions and appropriate triggers can respond to actions in a chain. If a target were moved by some other means before Hextech Ray resolves, it would not deal damage as the target would no longer be valid.

Sequence:

• An action card is played first to begin the chain
• Only reactions and triggers can be played in response to actions
• Once no one has more reactions/triggers, the chain resolves in first-in-last-out order
• After the chain fully resolves, whoever has priority can play another action to begin a new chain

Nuances:

• Actions can only ever be the first thing in a chain, never played in response to other actions
• Cards that say they can be played in showdowns still follow the action/reaction chain rules
• If a spell's target becomes invalid before resolution, it will not perform effects that require that target