NOTE: This Easter Egg can be done in Solo. It can be done with or without having completed all previous Easter Eggs in Black Ops III, and you will be rewarded with the achievement "For the Good of All". In case you completed the other Easter Eggs as well, you will also receive the achievement "A Better Tomorrow".
Let's get started...
In the spawnroom, upon looking to the direction of the Sheiva wallbuy, one can see two elevated islands carrying two tombstones each. Two tombstones are visible when looking from the alley leading to the launchpad going to the Origins area, and two others are visible when looking from the alley directly on the right of the House, behind the Sheiva wallbuy.
Inscribed on the tombstones are the names of Primis. The player must shoot the tombstones in the order in which the Ultimis souls were collected in the previous maps: Edward Richtofen, Tank Dempsey, Takeo Masaki and lastly, Nikolai Belinski. In case the names are not clearly visible, the order is the following:
The most right tombstone on the island closest to the House. (This is Richtofen's grave)
The most left tombstone on the island closest to the launchpad leading to Origins. (This is Dempsey's grave)
The most left tombstone on the island closest to the House. (This is Takeo's grave)
The most right tombstone on the island closest to the launchpad leading to Origins. (This is Nikolai's grave)
Upon completing this step properly, all four tombstones will ignite a small, red flame, confirming that you can move on to the next step.