Hello. I am a major fan of The Last Unicorn, both the book and the movie. And, I've been wondering, if one was to make a homebrew campaign loosely based off of it...how would it run?
I can imagine the Red Bull being used with the statistics for a Hadhayosh, though probably a bit differently (like changing the alignment to NE, or maybe even giving it the Divine Guardian template with an evil deity?)
Though that's the most I can come up with, and I'm wondering what others could suggest for something like this.
A campaign should have more going on than a couple of monsters. You can use the movie plot as inspiration, but the things that actual player characters do don't follow story outlines so neatly. I would worry about the story outline before figuring out monster stats. Does it take place in Golarion or some other existing world, or will you make up your own? What locations would you like to include? What conflict is taking place and what factions are involved? What past events led up to the current state of affairs? What are some possible outcomes to resolve the conflict? How far will you allow the players to stray outside of the major events of the story?