It … Its Exotic perk is Prototype Trueseeker, causing its rockets to aggressively hunt down enemies.
You will be heading into the boss chamber where you fought the Mindbender, the Hall of the Exalted. It’s a rocket launcher that was added in the Season of Opulence.

Decoding the Fragments. Released on the 11th of June, one week after the launch of the Season of Opulence, Truth allows players to complete a quest and welcome back the first Destiny's fabled tracking launcher, Truth… Killing the Ogre at the end of the Hall of the Exalted in the Jetsam on Tangled Shore. Complete a nightfall. It has the ability to lock on targets when aiming down sights, which makes the rockets follow them.
This means going into the remains of the Hive ship that rests at one end of the Jetsam of Saturn. As you find the fragments above, you will be tasked with completing the following: Kill 100 Hive on the Tangled Share, though powerful enemies grant bonus progress. Truth is a staple Rocket Launcher that originally appeared in Destiny 1. Your next destination is the Tangled Shore, where you will need to head to the Jetsam of Saturn. Truth is a staple Rocket Launcher that originally appeared in Destiny 1. Truth is a PvP-focused rocket launcher. Truth is an exotic weapon in Destiny 2. Weave your way on through to reach the final chamber. To get started with the Truth quest, you must first battle the new Hive Ogre boss in the Menagerie.