Step #1: Activate the Generators

Just that simple. Get all six (6) generators working.
Get more generator tips on the All Your Base Achievement Guide.
Step #2: Open the Underground Chamber

Travel to the Pack-A-Punch in the center of the map and collect the Gramophone down the stairs. The Gramophone, when combined with a vinyl record, will play music and open secret passages.
To find the first secret passage, place the Gramophone on the table near where it spawns, and then find the record.
A record should appear near the vending machine upstairs. Take it and place it on the Gramophone. It will begin to play music, and the stairs into the ancient civilization below the Excavation Site will lower.
This area will become important later. It is required to build the 4 Elemental Staffs.
Step #3: Build the 4 Elemental Staffs

To construct the Elemental Staffs, youll need to collect the parts hidden throughout the map and bring them back to the underground secret chamber you opened earlier.
To find the 4 Elemental Crystals, youll need to place the Gramophone with the correct disc (actually a vinyl record) next to the wall marked Crazy in each of the elemental tunnels.
For a full explanation, check out the Black Ops 2: Origins How to Build All 4 Elemental Staffs Guide.
Step #4: Complete the Ultimate Staffs

Once you have all four (4) Elemental Staffs, the team must complete puzzles in the Crazy place and around the trenches map.
See how to complete every puzzle, check out our walkthrough; Black Ops 2: Origins How to Build all 4 Ultimate Staffs
Step #5: 5th Staff Altar, Place Keys in 3 Mechs

Once all four (4) Elemental Staffs have been turned into the Ultimate Staffs, a 5th Staff altar will appear in the center of the chamber. Now, the players must re-enter the three (3) giant mechs and place matching staffs.
Ice Staff: Place inside Fraya, the Mech in the far left side of the map.
Thunder Staff: Place inside Thor, the Mech in the far right side of the map.
Wind Staff: Place inside Odin, the Mech in the center of the map.
Finally, place the Fire Staff on the new pedestal that appeared in the center of the chamber described earlier (it appears after upgrading all 4 Elemental Staffs) and Samanthas voice should play.
Step #6: Get the Thunder Fists

There are four (4) mech footprints with special chests scattered around the trenches. Kill zombies near the chests to fill them with souls.
Go to the chest in the crater near the Stamin-Up machine. Another is near the Jugger-Nog. The third is south of the Excavation Site, and a fourth is outside the Church.
Once all four chests have been filled, youll be able to get the Thunder Fists.
Step #7: Purify the Slabs

Next, the team will need to acquire special Stone Slabs to gain the G-Strike Beacon, sometimes referred to as the Odin Bomb.
Go to the Tank Bunker to find the slabs. Take them and place the items in the church water basin. Draw zombies near the basin and kill zombies to infuse the slabs with souls.
Once the slabs turn white, youll need to return them to the Tank hangar. Watch out for muddy patches walking in mud will revert the slabs back to normal, and theyll need to be purified again. Try using the Tank to return to the slab spawn location.
Continue to kill zombies until Samanthas voice is heard again. By now, the G-Strike Beacon becomes available grab it, and prepare to use it.
Step #8: Destroy the Seal

Enter one of the giant mechs any one mech will do. Inside the head, look for a bright red button.
Have a teammate with the G-Strike Beacon wait by the Seal located south of the Stamin-Up upgrade, outside the traversable area of the map. Dont miss!
Once the beacon is in place, have a teammate hit the button inside the giant mech to launch the strike.
Step #9: Send Maxis Drone into the Seal & Defeat the Panzer Soldat Horde

Next, prepare for a big fight. Bring the Maxis Drone near the Seal to send it in two (2) Panzer Soldats will spawn per player.
You can build the Maxis Drone at any point in Origins. Find the locations below:
Brain: Down the stairs, on a desk in the Spawn Room.
Frame: Near the Ice Tunnel, outside the road into the Tank bunker, and the tank entrance to the Church.
Rotors: All over the Excavation Site near the secret stairs, near the Pack-A-Punch, or near the lever inside the site.
The Maxis Drone only lasts 90 seconds before returning to the recharge table. Grab it and take it to the Seal to unleash the horde of Soldats.
Defeat them all, and the Maxis Drone will be unavailable until a later step.
Step #10: Destroy the Invisible Plane & Zombie

Use Zombie Blood to see a plane and a zombie that were previously invisible.
Look up in the sky and shoot down a plane spewing fire while affected by Zombie Blood.
With Zombie Blood, shoot the strange beast moving in circles around the Excavation Site. Collect the Maxis Drone from the body.
Step #11: Upgrade the Thunder Fists & Charge the Ultimate Staffs

Return to the Crazy place Staff room and kill 20 zombies. The fists will then upgrade into the Iron Fists. Grab them, and prepare for the end.
While in the Crazy place, place the four Ultimate Staffs onto their respective pedestals. Now youll need to kill zombies to infuse the staffs with souls.
Continue to kill until a portal appears. The achievement should now unlock, but theres still one step left to complete this Easter egg.
Step #12: Send the Drone into the Portal

Retrieve the Maxis Drone and bring it to the new portal in the Crazy place. The Drone will fly in.
Light will shine down from the portal. Walk inside to see the ending cutscene for Origins.