Scolopendium is a highly addictive plant extract native to the world known as The Fourlands. It is a potent hallucinogen, and strong enough doses will translate the mind of the user into another reality known as the Shift (which is apparently some form of dimensional nexus). Indeed, if the body of the user should die while the Scolopendium remains in effect, the mind of the user will live on in the Shift.
Scolopendium is illegal – although it does have some medical uses – and is known by several different street names, of which Cat is the most widely used.
Aside from its hallucinogenic effects, the physical effects of using this drug resemble those of heroin fairly closely, both in terms of the swoon it sends users into and also the effects of withdrawal.