This is one of my favorite units of the old Tomb Kings army. It's a converted skeleton cavalry unit that helped set the tone for everything else in the army. Here's a look at the entire batch:
As you can see, each horse and rider is completely unique, in pose and in colors. That was to reflect the Tzeentch taint of the entire army. What was gold armor had turned to 'mercury', and was now every color of the rainbow.
While you don't get bored painting every single figure differently, it can get a little crazy trying to make sure each one is unique, but yet maintain the same color set!
To learn more about the story of the army, I have this post:
He's also here:
Here's a peek at the green stuff work.