When summoning Riptide (with a When You Play Me effect that targets), can an opponent respond with Gust to bounce the targeted unit, and does this save the unit from Riptide's damage?

Ruling: Yes, the opponent can respond to Riptide's When You Play Me ability with Gust. If Gust resolves first and bounces the targeted unit to hand, Riptide's ability will resolve but cannot find the target anymore, so no damage is inflicted.

Sequence:

• Riptide is summoned and its WYPM effect is added to the chain with target declared
• Opponent gets priority and can respond with Gust targeting the unit
• If both players pass, Gust resolves and moves the unit to hand
• Players get priority again and pass
• Riptide's ability resolves but cannot find the target, so no damage is dealt

Nuances:

• You cannot play a reaction card in response to a unit being played itself (just the permanent entering play)
• You can react to abilities of the unit, including When You Play Me effects