The phrase "blow to kingdom come" refers to a powerful, explosive force that destroys something completely. Therefore, antonyms for this phrase would be words or phrases that signify something being preserved or protected. For instance, safeguard, conserve, defend, shield, and protect are all antonyms for the phrase "blow to kingdom come." These words connote a sense of safety, restoration, or preservation, which is quite the opposite of the sense of destruction conveyed by the original phrase. By using these antonyms, we can communicate ideas of protection and preservation instead of the devastation caused by explosives.