Here is the full list of all 15 Quell 4D achievements.
Wear two helmets at the same time
Kill 100 Animals
Exterminate 20 Slug Drones
Smash 50 Slug Eggs before they hatch
Prune 3 Slugs that have attached to your face.
Splat 10 Slugs attached to your face with the Shredder
Cook a Beefcake with the RPG
Waste 15 Ancient Triple Trunked Elephant Necro Shamans
Pick up five guns
Drink 10 Blood Bags
Boom 15 enemies with explosions
Kill the Ratfox Commander
Waste the Drone Queen
Own Necronomicus
Travel to space