The Parasite Exotic Grenade Launcher can be unlocked in Destiny 2 by completing the quest, Of Queens and Worms. This quest is available after completing the Witch Queen campaign and involves finding incubators in Lost Sectors and chatting with the new vendor, Fynch.
Of Queens and Worms quest – Parasite Grenade Launcher
The Of Queens and Worms quest is given to you by Ikora after you finish the Witch Queen campaign. Completing this unlocks the Parasite Grenade Launcher, an extremely strong Power weapon that may see a lot of use in both Crucible and PVE content.
Step 1: Meet Mara in the Enclave
Visit the Enclave and speak with Mara Sov.
Step 2: Birthplace of the Vile
Complete the Strike, Birthplace of the Vile. This can be launched directly from the Savathun’s Throne World map.
Step 3: Visit Fynch
Go back to Fynch and have a chat to him.
Step 4: Head into the Temple of Cunning
You will now need to head into the Temple of Cunning to find a Cryptoglyph rune. Open the map of the Throne World and highlight the quest icon to make it easier to reach it.
Step 5: Defeat Scorn
With the rune in hand, go around the Throne World and kill 100 Scorn. A good place is simply right near Fynch. As you’re doing this, consider using the Osteo Striga to level it up, allowing for further crafting at the Relic.
Step 6: Sepulcher Lost Sector
Head to the Florescent Canal in the Throne World and complete the Sepulcher Lost Sector.
Step 7: Sepulcher’s larvae incubator
You must now locate a larvae incubator at the end of the Sepulcher Lost Sector. When you reach the end, use the Deepsight ability to reveal a platform that grants access to a little window.
Step 8: Complete Patrols
Exit the Sepulcher Lost Sector and stay in the Florescent Canal. You must now complete three Patrol mission in that area. Bring up your Ghost to see the little Patrol icons on your HUD.
Step 9: Head to Queen’s Bailey
Like the fourth step, this step requires you to go off the beaten track and into the Queen’s Bailey to find another Cryptoglyph rune. Open the map, highlight the Exotic quest icon, and follow the marker to make this a bit easier.
Step 10: Metamorphosis Lost Sector
Go to the Miasma area of the Throne World and complete the Metamorphosis Lost Sector.
Step 11: Metamorphosis’ larvae incubator
At the end of the Metamorphosis Lost Sector will be another larvae incubator. Like the last one, use the Deepsight at the end of the Lost Sector to reveal a door behind a rock. Go through and place the worm on the incubator.
Step 12: Head to the Alluring Curtain
Next up on your journey to unlock Parasite is to head to the Alluring Curtain. When you reach the area, the object will appear to be missing – don’t leave the area.
Step 13: Deepsight cache
While you’re still in the Alluring Curtain, use the nearby Deepsight to reveal platforms. Climb these platforms and shoot the three lamps to ignite them. When all are ignited, a chest will appear down on the ground. Open it up to claim your reward.
Step 14: Extraction Lost Sector
Go to the Quagmire area and find the entrance to the Extraction Lost Sector. This is the final Lost Sector, and much like the previous two, you will need to get to the end to find what you need.
Step 15: Extraction larvae incubator
Fight through the Extraction Lost Sector to the end and use the Deepsight to reveal a path near the Hive statue. Place the worm on the incubator Grab your reward and head on out.
Step 16: Speak with Fynch
Have a chat with Fynch to complete this step. You will receive an item called the Hive Casing, which will take up a slot in your Power weapon space – so make sure you’ve got room.
Step 17: Complete Parasitic Pilgrimage
The final step in your quest to unlock Parasite is to complete the mission, Parasitic Pilgrimage. This is the last part for Of Queens and Worms and can be quite a tough mission.
For this final step, you will need to carry the worm through 16 Hive energy pools. You must move through all of them before the worm explodes. The strategy is to basically keep moving. Don’t stop and fight unless you absolutely have to, and even then it should only be done to give yourself enough room to keep running.
The main challenge will be trying to get the pools that are obstructed by moving Hive obstacles. It’s all about timing. Try jumping into the puddle and then immediately jumping out again as opposed to running.
As for the secret passage, look for the Deepsight and interact with it. Look at the floor to spot footprints that lead up the wall to a series of platforms that will get you to the next area.
Now you will need to steal Concentrated Hive Light by finding and destroying Hive crystals. Destroy the crystals and grab the Light that was in the trap.
With all that taken care of, you will need to head to the ritual site. Protect the worm from the Scorn and then continue onwards. Take the worm up to Mara, who is at the top of the tower in the Temple of the Wrathful. At this point you’ll be awarded Parasite and need to defend Mara while she completes the process.
Once the final mission is complete, you will be the proud owner of the Parasite Exotic Grenade Launcher. This thing boasts some wild perks that allow it to deal a ton of damage. Perhaps it will even become your go-to weapon for end-game PVE content? Take a moment to look over the Shacknews Destiny 2 Guide for a comprehensive assortment of guides and information.