I would really like to read it! Sadly, I don't imagine there's a great deal of overlap between the Merlin and the Supernatural fandoms, and the Merlin fandom has only existed for half a year, so I'll be surprised if anyone has written such a thing yet.

(From the very little I know about Dragonball Z, I'd be more inclined to cross it over with IX, certainly. I suppose Cloud has vaguely Super Saiyan-esque hair.)