The new Call of Duty Zombies map, The Tomb, introduces a returning Wonder Weapon: the Staff of Ice, originally from Black Ops II's Origins. This guide details how to obtain it.
Can You Get the Staff of Ice from the Mystery Box on The Tomb?
While the Staff of Ice, like its Black Ops II counterpart, requires three parts, you can indeed get lucky and find it in The Tomb's Mystery Box. However, this relies heavily on chance, and the Ray Gun is also a possibility. Using the "Wunderbar!" GobbleGum increases your odds, but doesn't guarantee success. Therefore, building the Staff offers a more reliable method.
How To Build the Staff of Ice on The Tomb in Black Ops 6 Zombies
Obtaining the Staff of Ice Monocle

The first part, the Monocle, drops from the first Shock Mimic you eliminate in a match. Simply interact with it to add it to your inventory.
Obtaining the Staff of Ice Head Piece

The Head Piece and Staff pieces require similar puzzle solutions and a subsequent lockdown survival. They can be obtained in either order.
To get the Head Piece, locate the cave painting in the Neolithic Catacombs. If the wall isn't illuminated, activate a Dark Aether lantern nearby (they respawn after a short time). Once lit, shoot the Roman numerals in ascending order (I-X). Completing this triggers a lockdown; survive it to claim the Head Piece. If lanterns aren't spawning, visit the Dark Aether Nexus and return.
Obtaining the Staff of Ice Staff Piece

For the Staff piece, go to the Tombs room and illuminate the Bull Mural (using the lanterns as before). Shoot the Roman numerals in ascending order (I-VIII). Survive the ensuing lockdown to obtain the piece.
Completing the Staff of Ice
With all three parts, head to the Dark Aether Nexus and interact with the central structure to assemble the Staff. Defend it during a zombie onslaught to complete the process. Using GobbleGums like Kill Joy and Free Fire can significantly aid in this defense.
This concludes the guide on obtaining the Staff of Ice in Black Ops 6 Zombies.
Call of Duty: Black Ops 6 is available now on PlayStation, Xbox, and PC.