There are situations so bad that anything that would end them is justified. Anything.
There is wisdom in facing a threat with a proportionate response. Sure, There Is No Kill Like Overkill, but it’ll likely cause a lot of avoidable collateral damage, and it’ll guarantee that tomorrow the next threat is stronger. But there are times when the threat is so great and things have gone so horribly wrong that there is no appropriate response. The situation is so dire that it justifies the use of any and every thing that might solve it, no matter how crazy, nonsensical, or horrific, regardless of cost or collateral damage.
Things are at the point where even summoning Godzilla, king of monsters and patron saint of collateral damage, could not possibly make the crisis any worse. The situation has crossed the Godzilla Threshold.
Once the Threshold is crossed, ANY plan, with even the smallest possibility of success, no matter how ludicrous, impossible, dangerous or abhorrent, suddenly becomes a valid option. This serves both narrative and authorial purposes. Suppose the heroes have an awesome weapon that nonetheless causes a lot of property damage, like a Kill Sat, or a captured or dormant monster. Or one knows a Dangerous Forbidden Technique that will put his life at risk. They have to use it, but it can’t be done lightly without portraying them as either careless or cruel. So the author contrives to make the situation call for its use in such clear terms the audience understands this was done as a last resort — and, if it’s handled properly, the audience doesn’t even notice.
Often, the threshold is engineered. If done wrong, it can cause some serious Fridge Logic. This is usually the case when the heroes’ actionsor failures to act cause the situation to cross the threshold. Usually, there’s an Idiot Ball (or Idiot Plot), a General Ripper, or Poor Communication Kills to thank for that.
Some plots center around avoiding the Godzilla Threshold and keeping the trigger happy person in charge of the “failsafe" from pushing the button. Sometimes, they even succeed.
The Godzilla Threshold is what happens just before the Willfully Weak character gives the "World of Cardboard" Speech and turns thePower Limiter off, uses the Forbidden Chekhov’s Gun, uses lethal powers, turns to the Nuclear Option, or casts Summon Bigger Fish. When begged, the All-Powerful Bystander may even be willing to lend a hand. In video games, this is the time to use items that are Too Awesome to Use.
Note that, as the Real Life section below attempts to show, using such options tends to create more problems; if the solution ultimately causes more/worse problems then you had before you may have a case of Pyrrhic Victory. Nice Job Breaking It, Hero and Won the War, Lost the Peace can be related in larger-scale stories. Of course, these only apply when the consequences are actually shown to begin with- if they pull it off without problems you may have an Informed Flaw.
Named for the Godzilla films of the late 1980s and 1990s, where Godzilla was evil again (in contrast to his heroic characterizations during the late ’50s, as well as the ’60s and ’70s) but people were still happier to see him because he was usually fighting something far worse.