I got one theory for you and I have some quotes to back it up. I think Psycho is a military grade of PCP here are some thoughts and quotes. -"bloodshot eyes" -"Psychological effects include severe changes in body image, loss of ego boundaries, paranoia and depersonalization. Hallucinations, euphoria, suicidal impulses and aggressive behavior are reported.", -"Intoxicated individuals may act in an unpredictable fashion, possibly driven by their delusions and hallucinations. PCP may induce feelings of strength, power, and invulnerability as well as a numbing effect on the mind" -"The analgesic properties of the drug can cause users to feel less pain, and persist in violent or injurious acts as a result." PCP greatly affects the aggressiveness of the user who's taking it, whether it be towards themselves or others. I believe that with military alterations they may be able to isolate the chem to a more violent and aggressive state and removing the side effects. As for implementing the crafting of Psycho in game, PCP is mostly chemical in nature. It can't be found in a natural form such as, cocaine or marijuana (THC). I believe one way in creating Psycho in game is take Chemicals from similar aggressive mobs and combine them along with some other natural compounds. For example: (Empty Syringe + Abraxo Cleaner + Turpentine + Night Stalker's Blood = Psycho)