** It has been pointed out to me by Time Paradox 5 that you can also get this achievement without the shield. You just go down to the pit and shoot zombies in the arms and legs and throw grenades at them as well **
To complete this achievement you need to first build the "Brazen Bull" shield and then kill zombies in a room known as "The Pit"
You can know your location at any point in time by checking the top left corner of your screen.
The locations for the "Brazen Bull" shield parts are as follows:
*These are not my images they are used from the
"IX" Easter Egg Reddit discussion----------------------------------------
Part 1
Ra Altar RoomRa Altar Room----------------------------------------
Part 2
Zeus Altar RoomZeus Tower: EntranceZeus Tower: Bath Room-----------------------------------------
Part 3
Odin Altar RoomOdin Tower: EntranceOdin Tower: Cauldron------------------------------------------
After finding the shield parts you want to proceed into the underground area. "The Pit" location is the very close to where the first box spawns and has an area in the middle of the room with tons of bodies in it.
You will notice in the corner of the room is a workbench where you can build the shield and then proceed to shoot zombies in the room with the shield special ability using "LT + RT"