For this step, players must retrieve five skulls around the map with the Hell's Retriever.
The skulls can be seen when in the Afterlife. If your team is having trouble locating the exact position, have one player go into the afterlife and shoot electricity at the location. It seems the skulls do not have to be collected in a specific order, but it's best to retrieve the one in the warden's office last.
Cell Blocks Skull
One skull is located in a cell just outside the library. A skull is on a shelf, but you need to aim the Hell's Retriever at the toilet. Throw it to retrieve a skull.
One skull is located on the rooftop. Head to the left side of the roof where there are no obstructions from looking over. Throw the Hell's Retriever slightly towards the corner of the rooftop that's jutting out.
Docks Skull 1
One skull is located at the top part of the docks near Jugger-Nog. Throw the Hell's Retriever at the lamp post (street light, whatever) that's above the entrance / exit to the docks.
Docks Skull 2
One skull is located at the bottom of the docks. Look over to another dock to the right of the tower trap. Throw the Hell's Retriever on the third wooden pillar to obtain the skull.
Warden's Office Skull
One skull is located on a power line outside the Warden's Office. Look out the window to the right of the Speed Cola machine to see the power lines across the street. Throw the Hell's Retriever towards the left part of the wooden + on the power line post.
It's best to get this skull last because a Blundergat will appear out of the desk in this room after all skulls are collected.