A bit late to the game here. Too many things going on lately and not enough time in the day. Anyway, here's the two i came up with quickly.
1. Is of a dreadful unicorn thing with a twisted gnarled root looking horn, being ridden by some dark character. The poor fellow in the front is cowering on a pile of bones...kind of a judgement scene. I want to contrast the darkness of the unicorn/rider to the paleness of the naked guy and the bones.
2. Is of the same scene but looking past the dark figure/unicorn to the poor soul.
and the unicorn demon horse will look somewhat like this:
Maybe working on a young adult project makes me crave dark evil things?