Scenario:
* You activate Creature Swap, targeting a monster on your opponent's field.
* Your opponent Chains Windstorm of Etaqua, targeting your Creature Swap.
Outcome:
* Creature Swap is negated. Chain Windstorm of Etaqua specifically targets spells and traps, so it successfully disrupts your Creature Swap.
* The effect of Creature Swap does not happen. Your opponent's monster stays on their side of the field, and your chosen monster remains on your side.
Important Considerations:
* Timing is key. Windstorm of Etaqua must be chained to Creature Swap to work. If you activated Creature Swap and then your opponent activated Windstorm of Etaqua on their turn, it would have no effect on Creature Swap.
* Other cards could be involved. If your opponent had a card like "Solemn Judgment" or "Solemn Strike" that they could activate in response to your Creature Swap, it would have to be activated before Windstorm of Etaqua.
* Creature Swap's secondary effect: Creature Swap's effect is not completely negated. You can still activate the secondary effect of Creature Swap, which allows you to discard a card and add a Level 4 or lower monster from your deck to your hand.
In essence, Chain Windstorm of Etaqua negates Creature Swap's primary effect of switching monsters, but it doesn't completely negate the card. You can still take advantage of its secondary effect.