Chimeran Boiler

Chimeran Menials are created when male Humans are transformed just enough to lose their personalities and free wills, with the resulting creature being weak and pathetic compared to their more advanced brethren, and being limited to simple physical tasks within Conversion Centres. Human females who undergo the same process aren't much more powerful, but they come out a substantially different creature. 
 
Chimeran Boilers are the result of women who have been transformed by the Chimeran virus; their hands have atrophied into uselessness, but this belies their simple purpose. Boilers are kamikaze units, with their grossly expanded heads containing sacs of volatile chemicals which they can deliberately mix once they are within close range of an enemy soldier. At this point, the Boiler's head explodes violently, killing the creature but heavily damaging their enemies. Curiously, the bodies of Boilers are extremely tough and resistant to damage, even more so than the standard Chimeran Hybrids. Their weakness lies in the necessary thinness of the skin around their chemical sacs; shooting one in the head with a single bullet will prematurely detonate the sac, killing the creature without harming you. To make up for this, Boilers are generally deployed in very large numbers.