Nargil was the cerebrate of the Fenris Brood. Its tasks were to locate creatures which could be assimilated by the Swarm, as well as hunt down enemies of the Swarm. Nargil's minions were excellent trackers and Nargil itself could intercept enemy transmissions.
The following section contains information from StarCraft: Insurrection.
- Main article: StarCraft: Insurrection Zerg Campaign
Nargil offered assistance to a new cerebrate created by the Overmind. The Fenris Brood fought protoss 7th Fleet forces in space, led by Executor Andraxxus, securing access for the new brood to descend to the surface of Brontes IV. The new brood was ordered to hunt down protoss commander Syndrea, but when it reached her, Nargil told her that the Overmind wanted her alive.
Nargil was able to "eavesdrop" on a conversation between the terran Black Morgan, a dropship pilot and former member of the New Dresdin Outlaws, and her ex-boyfriend Jack Frost, revealing she had left them. The New Dresdin Outlaws were enemies of the Swarm but had taken to hiding so the zerg couldn't find them. The Overmind said Black Morgan could be infected with a queen's parasite and followed this way. Nargil suggested the new cerebrate's forces attack her openly, which would cause her to flee and therefore lead the zerg to her companions.
Executor Andraxxus was driven to rage by the attacks of the zerg, which could interfere with the new brood's task of attacking the rogue Carpenter's Brood. While the new brood did so, Nargil was tasked with attacking Andraxxus's 7th Fleet forces.