Genestealer Brood

Genestealer broods outside the range of any Synapse Creatures do not use the Instinctive Behaviour rules and instead take Morale checks and Pinning tests just like ordinary troops.

This special rule is automatically lost by an independent character joining a unit that does not have this special rule, and vice versa.

There are many variants of this rule: Fleet of Foot, Fleet of Claw, even Fleet of Hoof. Title aside, all models with these abilities are treated similarly. In a turn in which models with this rule do not shoot or use a psychic power that replaces shooting, they can move an additional D6" in the Shooting phase, ignoring penalties for difficult terrain.