What's the best GURPS thaumatology system for a minor godlike boss being?

[Prince Charon]

Originally Posted by SolemnGolem

So that leaves Realm Magic. I looked at Verb-Noun magic and thought it looked interesting, but then I was told that RPM was a worked example of that, so I stopped looking too closely at Verb-Noun.

RPM is a worked example of Path/Book Magic that uses significant elements of Verb-Noun, though, or you could say that it's a worked example of both, in much the same way that some versions of Realm Magic could also be considered (rather tweaked and energy-intensive) worked examples of Verb-Noun Magic. How fast Verb-Noun Magic is depends on how you the GM tweak the version you use. That said, Realm Magic is probably still more fitting for a godling.