The first Conquest Icon was created and placed on Neibaum Prime by the Lord Marshal Kryll. It was created to serve as a memorial to Baylock and the brutal battles that had taken place on the planet in the Carthodox War (a conflict against another religious cult, the Carthodox) which was the costliest Necromonger conflict at the time. Baylock was another casualty in this war, but he was killed in a landing accident near the war's end, rather than in battle. Thus, the Conquest Icon was established on the planet to immortalize Baylock and the other Necromongers who were lost to the Carthodox. By creating this statue, Kryll superseded the Necromonger law that banned personal icons.
Zhylaw, the Lord Marshal whose regime followed Kryll's, created many Conquest Icons that served not only to be a memorial of the battle that took place where it landed but also to start that battle. The campaigns he led across the planets of the Coalsack, Aquilan, and Cazar systems often only had Conquest Icons remaining to remember the battles that took place.
The Icon is easily the most powerful weapon in the Necromonger arsenal - it is not only used as a psychological weapon in the pre-invasion of a planet, but also at the beginning of the invasion of that planet. It carries thousands of fighters which are launched right after the Icon's landing. At the end of the planetwide campaign, as the defeated or victorious Necromongers evacuate, the Icons are used to reduce the planet to a lifeless world of ash. The Icons are heavily armored and it is nearly impossible to damage them, let alone destroy them.
Conquest Icons are the advance wave of any Necromonger conquest. They are sent past the soon to be invaded planet in groups, disguised as a passing comet, but when nearing the planet they break up and land on the planet. They land on designated areas of the planet, crushing anything beneath them (which can encompass entire city blocks). They then unleash the first wave of the Necromonger assault: squadrons of Necromonger fighter ships. These ships serve to overwhelm or distract the defending forces that could inflict damage on the soon-to-arrive second wave - Warrior Ships carrying the invasion force, and the Basilica, which contains the reigning Lord Marshal, Necromonger commanders, and other key figures such as the Purifier. The survival of these ships is key to the battle's victory and the survival of Necromonger society, and so the Necromonger fighters are used as both a screen to keep any dangerous enemies away from them, and they also serve as fodder to distract the same enemies from the important ships.
When the battles across the planet end in either victory or defeat for the Necromongers . When they prepare to leave, the Conquest Icons serve another purpose. As part of the Ascension Protocol, each Conquest Icon contains a large energy orb that launches from in between the three faces. If the Lord Marshal orders the planet's destruction, the orb slams into the ground below the icon and the energy spreads outward quickly, incinerating all around the Icon for miles as do other Icons , simultaneously. The unfortunate planet is reduced to a lifeless and barren world and the surface burnt to ashes.
After the Conquest Icon is activated, it is left on the attacked planet. These imposing statues serve as psychological weapons for the Necromongers before they attack the next planet or system - the destroyed worlds with only these massive structures remaining spread fear and paranoia throughout nearby worlds. For this reason frightened residents of nearby worlds often refer to Conquest Icons as the "calling card" of the Necromongers, and refer to the Necromongers themselves as simply "The End".
A smaller type of Conquest Icon (the size of a staff) is brought into combat by a chosen Necromonger whose duty is to set it up at powerful enemy positions so that the position can be destroyed. These Necromongers accomplish (or at least attempt to) their duties with stubborn ferocity. Even if they have been shot several times, they will still try to place the Icons in the designated position before dying.
Once placed, the Icon automatically launches a smaller energy orb into the air as its larger cohorts do (by this point the initial Necromonger attackers are usually defeated, leaving no chance of friendly fire). If a nearby Necromonger commander gives the order to activate the Icon, the orb will be launched and will be subsequently slammed into the ground, killing all enemies in a small radius beneath it (who are usually confused and bewildered by the orb's appearance, and thus immobilized below it). While the orb does not spread out and destroy everything around it in a large radius, it is still extremely deadly to anyone standing approximately ten meters (or less) away from the Icon.
Toombs' commentary on Conquest Icons is as follows: "I've got no dealings with Necromongers. In my opinion, they're all bad for business--them and their bulls*** beliefs. Seen their ships, their conquest icons? Two thousand feet of bad sculpture. Screw setting up shop on some planet. You never know when one of those things is gonna drop in your backyard. For my money, a merc ship's the safest place to get some shut-eye."