We'd Rather Be Turned to Stone
We're not shouting at you, folks: MEDUSA is in all caps everywhere in Mortal Engines. If it's an acronym, we're not told what it means. Mighty Energy Death Used to Slaughter All? MEDUSA is a relic of the past, and by past, we mean our time—a time where weapons of mass destruction could be anywhere, and all it takes is the push of a button to exterminate an entire nation of people.
MEDUSA shows us just how horrible and unpredictable technology can be sometimes. Magnus Crome doesn't quite understand it, but that doesn't stop him from using its power to blow up his enemies. Unfortunately for him, and for all of London, it backfires and destroys them all in the end. Hey, wasn't the fabled Gorgon defeated by her own power?