re: #193 b_sharp

Did you mean Culex tarsalis?

To clarify;

The Culexus Assassins are the most sinister, feared, and hated of all Imperial Assassins. They are null-entities in the warp, their unnatural lack of a presence inspiring even in non-psykers a sense of unease. To psykers their mere presence is terrifying, invoking panic. In the confusion caused by this fear, the assassin can move in on its target and eliminate them. To purely psychic entities like daemons, they are invisible.