This is my WIP Night Lords Deamon Prince. I wanted something truely nightlordish so I decided to, instead of using a deamon, which the night lords reject, I would use an slave deamon. Finding the right model for the lord was hard, but I came down to the Zacharias Dragon from the Vampire Counts fantasy line, or the Dark Elves dragon from Fantasy. I chose the Dark Elves dragon, because frankly, it's just more nightlordy. The rider will be armed with a large lance (the etherlance deamon weapon) and the model will have deamonic essence to account for the wound for the rider.
The rider still needs green stuff work, arms and head, but you get the basic look of him.