The Ascension Protocol was the last phase of all Necromonger invasions. Once that the Necromonger forces have extracted the new converts from that civilization, the Lord Marshal would activate the Conquest Icons on the planets surface which would send a wave of energy which would extinguish all life on a planet. Due to the half-dead nature of the Lord Marshall, as the other Necromongers are merely quarter-dead, only he can control the lever which detonates the orb. The Necromongers would then leave the planet lifeless, leaving only the used Conquest Icon. It is interesting to note that the Necromonger uses smaller staff-like version of the conquest icons that have the same effect, but with a shorter range.
The use of the Ascension protocol was when the newly formed fleet of the Necromonger Empire, during the reign of Naphemil, departed from Asylum, which became known among Necromongers as Ascension Day. 
When Riddick unintentionally becomes the new Grand Marshal after the invasion of Helion Prime, he deactivates the Ascension protocol and the Necromonger ships leave the planet to go to the Underverse.