During Kerrigan's resurgence, Abathur developed the corpser strain in a scantipede held captive by the protoss in a concealed research facility on the planet of Cantar. After collecting the essence of the scantipede, the corpser was formed. The corpser utilizes the parasitic injection ability of the scantipede: its acidic saliva melts away the flesh of its target, allowing its parasites to burrow and gestate in the target. Upon death, roachlings break free.
Enemies damaged by the corpser will spawn two roachlings if killed quickly.
Since the roachlings can act as cannon fodder, corpsers are effective against massed numbers of enemy troops, such as marines, zealots, and zerglings. The roachlings, however, are easily destroyed by splash damage attacks and deal poor damage per attack, so corpsers are less effective against larger targets. Despite this, the roachlings can still draw shots from attacks that would otherwise hit the corpsers themselves.