The Tyranid biomorph known as the Lictor (Tyranicus Chameleo) is a specialised evolutionary development of the Tyranid Warrior, highly adapted to a role as a scout in the vanguard of any Tyranid swarm's advance. Lictors move ahead of the swarm, seeking out pockets of resistance to be eradicated and native life forms to be absorbed. Able to move swiftly and without sound through even the densest terrain, and concealed by a chameleonic carapace that renders it all but invisible to the naked eye, a Lictor can remain hidden until it chooses to strike. It can wait motionless for days, unnoticed by its victims, an unseen herald of approaching disaster.
These opportunistic hunters tend to avoid confrontations where they would be outmatched, silently stalking their prey from the shadows. Stalking Lictors also serve another deadly purpose than simple slaughter; exuding a potent pheromone trail which draws other Tyranids to the slaughter. The larger the concentration of prey, the stronger the response and the more irresistible the lure. As scouts, Lictors are able to operate outside the Hive Mind's synaptic web, so they do not need to always remain close to a Tyranid synapse creature.
When the time comes to strike, Lictors are brutally efficient, with a whole arsenal of bio-weaponry that includes mantis-like claws, talons that can pierce steel, barbed flesh hooks and feeder tentacles. The feeder tentacles are tipped with sharpened bony plates that can pierce a victim's skull as easily as they can poke through eyeballs and sockets. They are used to lobotomise a victim so that the Lictor can swiftly devour its brain and absorb its memories in biochemical fashion. Thus, in death, the enemy reveals more to a Lictor than it ever did in life, betraying the whereabouts of comrades and revealing any weaknesses that might be exploited.
- Codex Tyranids (5th Edition), p. 41