Some Scrap monsters want to be destroyed to trigger effects.
Destroys one of your monsters.
Since this is a quick-play spell you can set it and then activate it in response to an opponent's card that would get rid of one of your Scrap monsters, so that you gain additional advantage.
You can target these monsters with Scrapstorm for destruction. Scrap Kong, Scrap Orthros, and Scrap Worm allow you to retrieve Scrap monsters from your graveyard when they are destroyed. Scrap Shark searches a Scrap monster from your deck when he is destroyed. Scrap Golem and Scrap Chimera special summons monsters you can destroy with Scrapstorm to gain more searches and advantage. When you target a monster for destruction with Scrap Breaker you can chain Scrapstorm to instead destroy your targeted monster with Scrapstorm to get more utility out of it.