From Destinypedia, the Destiny wiki
Pike Dregs are among the most dangerous of Dregs by virtue of their Pikes. They can unleash a tremendous hail of Arc fire that can kill an exposed target in seconds, and are usually fought in wide areas that limit one's access to cover. Gangs of three Pike Dregs can be encountered roaming any Patrol Zone with Fallen, announced by the message "A roaming gang of Pikes is close". These will usually stop to fight any enemies they come across and can disrupt the progression of a Public Event, but will usually retreat after a while. In high level content, such as Nightfalls, they will stay in their areas, and quickly destroy Sparrows with their weapons. That said, they are still Dregs, and are never equipped with Absorption Shields, meaning they are still much vulnerable to being sniped off their vehicles by any sort of weapons, and will not survive a destroyed Pike's explosion.
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