There's a new secret Exotic weapon in Destiny 2: Outbreak Perfected: an updated, super-powerful version of the pulse rifle Outbreak Prime from Destiny 1. The gun is hidden, however, and not easy to get. Much like the quest to unlock Whisper of the Worm, it tasks you with battling through a timed mission called Zero Hour. This mission is packed with tough fights, platforming puzzles, and a big boss battle.
Check out the video above for a look at how to clear the normal version of Zero Hour (there's also a Heroic version that'll help you unlock the Outbreak Perfected catalyst). The mission is something of a maze, with lots of fake paths and dead ends designed to creep up on that time limit. The video will give you a look at the correct path through the full mission, which takes place in the ruined Tower from the beginning of Destiny 2. It will also show you how to take down the Fallen boss at the climax.
What the video doesn't show is how to start the mission, which requires you to find a particular item hidden on Titan, then solve some riddles to figure out where to go next. If you prefer to figure that out on your own, we've got where to find the start of the Outbreak Perfected quest detailed here; there's also a full Outbreak Perfected guide on how to start the quest, unlock the mission, and complete Zero Hour.