Psycho appears as a form of injected drug composed of strange, unknown chemicals of military origin, that comes with its own unique delivery system. It was designed at the orders of General Chase specifically for military use. It increases a soldier's damage resistance, and its dampening effect on higher brain functions make for tough, but uncontrollable, troops. This drug was very popular for human-wave assaults.
Slasher is a chem which combines the effects of Med-X and Psycho into a single drug. It is possible to combine the effects of this drug with Med-X to gain a 50% boost to damage resistance. It will not stack with Psycho.