As a blog with three Tyranid addicts, we of course had to pick up the first of the three dataslates to supplement the army. As Black Library released earlier in the week, in addition to the fluff (which I haven't read yet, but I'm looking forward to), there are five formations to be added to the army.
The first formation is a Lictor Forest Brood, which consists of 5 Lictors in a single brood. This brood gets their Stealth upgraded to Shrouded in Jungles, and also can infiltrate within 6" of an enemy model if they begin in a forest.
The second formation is Manufactorum Genestealer formation, which consists of 5 Genesealer Broods, which cannot be larger than the minimum squad size of 5. The formation gets Hit & Run, and can infiltrate within 6" of an enemy unit if deployed in a building or ruins.
The next formation is Deathleaper's Assassination Brood, which is Deathleaper and 5 solo Lictors. This formation gets preferred enemy against all characters and independent characters. Additionally, all enemy units within 12" of a model from the formation suffer -1 to their Leadership.
The fourth formation is Broodlord's Hunting Pack, featuring 3 Genestealer Broods with a single Broodlord attached to one. When arriving from reserves, the unit can be placed in an unoccupied building, or in ruins at least 6" from enemy models. Additionally, when the broodlord is deployed, you nominate a single enemy unit and all models from this formation gain preferred enemy against that unit.
Finally, there is the surprise formation, the Gargoyle Bio Bombs, which consists of 3 Spore Mine Clusters and 3 Gargoyle Broods. Additionally, if a spore mine cluster is within 6" of a gargoyle from this formation at the beginning of its move (run or charge included), it will move the regular distance instead of a halved distance.
The Dataslate concludes with two themed missions and a teaser for the next installment, Tyranid Invasion:
Having skimmed through the dataslate, I'm of two minds. One, I'm looking forward to the fluff that is more detailed than that of the codex. I also think the formations could be fun to play with in a relaxed setting, particularly in a themed campaign. That said, none of the formations, being formations, will ever see competitive play (or at least they shouldn't, Tau screwed that up out the gate). And even if they did, I'm not sure how much of a gap they could fill in a Tyranid army. Honestly, one of my favorites might be the gargoyle bomb, since it would allow me to field Gargoyle Broods in a screening role while filling up my regular fast attack slots with Harpies and Crones.