Here are some synonyms for marauder:
* Raider
* Pillager
* Looter
* Plunderer
* Bandit
* Robber
* Freebooter
Example sentences:
* "The marauding army swept through the countryside, leaving nothing but destruction in their wake."
* "A band of marauders attacked the village, stealing food and livestock."
* "The pirates were notorious marauders, attacking ships and coastal towns."