Everything has a weakness, every lock has a key, every curse a loophole, and the flaw will come into play to bring down the device.
This applies to basically every "immovable object" and "unstoppable force" in fiction, be they objects, characters, science, or magic. The idea is twofold: inside the story, the creator of the device or technique may incorporate a Necessary Drawback that will make it [...] [tvtropes.org]