When Lictors debuted, they had a haematoxin ability that meant that when a model gets wounded by them, it is guaranteed to slowly die. Basically it was a 2e Implant Attack, and these days they're one of the few large combat-oriented Tyranids who
can't take this biomorph. Additionally, their fluff lists many instances of them eating a prey-thing's brain and gaining intel from assimilating their memories, and of them targeting prey leaders for assassination.
So, here's the house rules I propose, inspired by
my alternative Malanthrope rules:
Lictors have Implant Attack biomorphs for no extra cost.
Special rule: Assimilation.
The Lictor's role being to act as a scout for the Hive Mind to learn about its prey, it has evolved Feeder Tendrils that enable it to devour the brains of prey and assimilate their memories to gain valuable intel. The knowledge of prey leaders with high-level strategic intel are of particular value to the Hive Mind. If a Lictor unit survives the battle having inflicted Instant Death on any
HQ units that are Independent Characters or Monstrous Creatures, the owning player scores an additional Kill Point or Objective for each of these killed units.
Note that some
HQ units may take a retinue which makes them count as being a member of a unit. These models will still yield Kill Points or Objectives even if they are not behaving as Independent Characters or Monstrous Creatures at the time of death!
Note: it is recommended that sporting players consider C'tan and the Eldar Avatar as having the Eternal Warrior
USR.