When Voidraker is in play, there are two animations in differnt places. It flashes on and off between the two. Check it out, it nearly made my face bleed!
http://forums.poxnora.desertowlgames.com/index.php?threads/hekatian-voidraker-spazzing-out.4739/ This has been noted and is on their todo list.
I checked it out and the Voidraker looks fine. It could be one of your files is corrupted which should be resolved by using the repair option on the Pox Nora launcher or you could uninstall and reinstall.
