Purple Cyst

Before you can complete this quest, you must have obtained the Blundergat and opened the garage in the twins swingset step of the main quest.

You'll need to collect seven total items to offer to the Purple Cyst that can now be found in the Green House Backyard. Below are the seven items and their locations.

Head

Guts

Bone

Car Battery

Bucket

Dog Collar

Chunk of Meat

Starting the Ritual

Once you have all seven items, place all seven down at the Purple Cyst by interacting seven times, then hold interact once all seven are placed to have the cyst eat all the items. Once eaten, the cyst will now be a soul box which you must fill, and once filled, it will spawn four HVTs: Heavy Zombie, Rad-Hound, Mimic, and Doppelghast.

These HVTs are extremely tanky, so be sure you have a good weapon, scorestreak or similar to take down these enemies.

Once the final HVT has been defeated, it will drop a Flawless Aetherium Crystal, 2000 Salvage, and a Random Perk Can for you to collect, and these rewards are fixed so it does not matter at what round you complete this quest.