Hi Guys!
It's maybe a little bit late, but I have found a video, where you can see, how to solo the Headless Horseman if you are a warlock. (Should be possible with every caster- class)
Maybe, it's useful for private Servers.. or for the next year, wenn the Halloween- Time begins..
Here is the video: [ame=http://www.youtube.com/watch?v=G7Z9NyAgxCs]YouTube - Solo the Headless Horsemen (not my movie)[/ame]
I hope, that it's useful for you..