In order to build the occult altar, players must right-click upgrade from the altar they have built, with the required materials dependent on the altar built. For example, upgrading the Ancient altar to the occult altar will require 1 lunar signet, 10,000 astral runes, 1 Arceuus signet, 5,000 blood runes, and 5,000 soul runes.
The crystal saw boost is applicable, making the minimum requirement level 82 Construction with a +5 boost from an orange spicy stew.
Note: the rune pouch is not compatible with construction; ensure that your runes are outside of the pouch before attempting to boost/craft.
Note: Although the recipe lists that Pharaoh's sceptre (uncharged) can be used, a sceptre with any charge level will be acceptable.
During development, the altar was called "Altar of the Gods". It was presumably changed as only the Ancient Magicks are associated with a god — Zaros.
The books on the altar contain Morse code, which can be translated, from left to right, as: "cosmic comic" in the Lunar book; and "darkaess[sic] corrupts" in the Dark book.
The misspelling of "darkness" may be an intentional reference to Arceuus, as it is pronounced in a similar fashion — (dar-KAY-us).
The "A" (▄ ▄▄▄) may simply be a mirrored misspelling of "N" (▄▄▄ ▄).