Lorelei's Insane Crossover Challenge

loreleif was incautious enough to issue an insane crossover challenge, and I've seized the moment to dust off a snippet of mad crossoverish strangeness that I've had on my harddrive for years. Not only is it an insane crossover; it's insanely obscure. But no-one said anything about that...

( And so it came to pass, some time during the roaring 20s of the 5th century... )