The Warmind DLC added a bunch of amazing things to Destiny 2, among them is a returning weapon from Destiny 1 that was a big favourite for Guardians, the Sleeper Simulant. This weapon was a Fusion Rifle with shots that would bounce off of surfaces and hit enemies around corners in much the same way as Hard Light’s. The catch to getting Sleeper Simulant this time around is a big old quest. Don’t worry about the details, we’ve got a guide here that’s going to take you from start to finish and land you with that brilliant new Exotic for your collection, and your own self satisfaction.
Source: N4G PC Destiny 2 Sleeper Simulant Quest Guide