If a friendly unit from Codex: Tyranids arrives on the battlefield via Deep Strike, it will not scatter so long as the first model in the unit is placed within 6" of a model with this special rule. Note that the model with the Pheromone Trail special rule must already be on the table at the start of the turn for this ability to be used.
Building an army? Create, validate and share your list with New Recruit, army builder for Warhammer 40,000 7th Edition and many more games.
Try the builder