According to Richtofen, the Ragnarok DG-4 is another way Group 935 was successfully able to weaponize Element 115, with the element being the power source for the DG-4 to function.
The Ragnarok DG-4 is essentially the Zombies equivalent to the Gravity Spikes from multiplayer. It can be planted onto the ground, creating a forcefield capable of trapping zombies, as well as Panzersoldats.
It is a Specialist Weapon, and acts in the same way as the Annihilator, Apothicon Swords, Skull of Nan Sapwe and the Gauntlet of Siegfried in which players can use it repeatedly for a limited time to slam down, creating an electric shock wave which instantly kills nearby zombies, before needing to be charged up again by killing Zombies. The spikes can also be tossed to the ground to create a lightning trap, zapping nearby zombies which come close to the energy ball.
To find the three pieces required to construct the Ragnarok DG-4, a player must:
Kill the first Panzersoldat. The Panzersoldat will drop the part upon death, like the Fire Staff piece from Origins. Should a player fail to pick up the part, killing the next Panzersoldat will cause the part to be dropped again.
When the V2 rocket is about to test-fire, on the left staircase behind the rocket (looking from the blast doors at the rocket), a lever with a red light above will turn green when activated, and will light a console to the right of the teleporter. The player must then survive in the tunnel until all three lights on the console are green (when the test-fire is finished), then interact with the console which will cause the part to spawn in the teleporter. Additional zombies (including flaming and electrified ones) will spawn in, but do not count toward the zombie count for the round, nor do they give points to the players. Note that the switch in the Undercroft that spawns a Death Machine power-up will also activate the rocket test.
In the Bastion area, after turning on the Death Ray, a piece will float above the bastion. This part will spawn in one of two places which can be accessed by using the Wundersphere pad next to the Demon Gate arrow spawn or near the Kuda wallbuy to launch and grab it.
In Revelations, the Ragnarok DG-4 can be acquired from the Mystery Box. If they player bleeds out with the Ragnarok, they will have it again once they respawn.