Stallion is one of the drugs available in Bay City. Stallion causes a flood of adrenaline and testosterone, causing men who take it to become exceptionally erratic for extended and uninhibited sexual activity but can cause violent behavior in higher doses.
Takeshi Kovacs bought Stallion, along with a large number of other drugs, from a street dealer.
It was later revealed that Laurens Bancroft was drugged with Stallion, which caused him to have a violent sexual encounter with a hooker that ended with him snapping her neck and spine, smashing her stack, and giving her a real death.