Occupation Monoliths are placed next to a settlement monolith by the AI. The Occupation Monolith itself places 3 normal AI troop spawners so the AI can occupy the player settlement.
The Occupation Monolith looks like a mix between a monolith and a common AI spawner. It has a pinkish glowing bulb in the center and a powerflux like the AI spawners at the bottom. At it's center is a giant red beam, pointing up towards the sky, similar to a power well. The beam pulses in size, at times disappearing completely from view.
This monolith can be destroyed with any weapon. The pinkish bulb in the center declines with the hits the monolith takes.
Only unarmed settlements (no weapon tokens placed) get occupation assaults. Therefore, another option to stop an occupation is to place a weapon token inside the settlement. Warning: In this case surviving AI troops will try to destroy the placed weapon token to continue the assault.