Monster Hand

This side quest has players enter the Dark Aether and shoot four buttons within the Medical Bay to release a Monster Hand, which if you feed it 15 Zombies will reward you with a free Legendary Rarity upgrade to your currently held weapon.

Release the Monster

Head into the Dark Aether and make your way to the Medical Bay, and to the left of Speed Cola in that window, will be five red buttons, one next to each of the doors.

You have to shoot all red buttons except for the close-left button, to turn the lights above their doors green, and once all four buttons have been shot, the final close-left door will shine a green light through its window. Finally, you'll want to shoot the final close-left red button when zombies are running by to release the Monster Hand and feed it those zombies.