Stalker: Call of Pripyat → Quests → Hunt 2 (Unknown Mutants)
Zveroboy will give out 5,000 rubles collected by stalkers.
Stalkers have discovered unknown mutants in the tunnels beneath Jupiter. They need to eliminate the threat. The unknown mutants turn out to be a pair of Burers. Trying to shoot them down could result in death, and it's difficult. However, the knife proves to be a valuable asset – it prevents the Burer from using its abilities, forcing it to parry attacks, while the Burer itself only needs a couple of hits.
See also:
Space Pistol. Terraria and Meteorite