The result of a Blisk Spore infecting a host. It is a heavily-armored organic life-form (usually a mutated human).
The first Blisk Mutant appears in the abandoned tunnel networks in Albion. The mutant is Agent Oranchov who shoots a container of Blisk Spores, which causes him to mutate into a Blisk Mutant.
To take one down is to use the Anal Probe to disintegrate the Blisk Possession, then finish the damaged Possession down with the Disintegrator Ray or Zap-O-Matic.