The legs and head are from the Dark Angels veterans models, I believe, while the torso is from the Space Marine Commander box. His staff is part power axe, with the winged skull coming from I think a command squad sprue, and the skull at the bottom is from a Vampire Counts box of skeletons.
I wanted him to look like he was advancing confidently and unstoppably towards some foe, either getting ready to hit it with a psychic power, or stopping the psychic attacks of a Chaos sorcerer.
