Trolls were a large and monstrous race of humanoid beings that served the Dark Forces of Middle-earth. They were often unintelligent. The trolls were said to made in mockery of ents . During the War of the Ring, trolls were used in evil armies of Middle Earth. For example, cave trolls were used in Moria and battle trolls were used by Gundabad and Dol Guldur (film), while mountain trolls and Olog-hai were used in Sauron's own armies. They were used mainly as shock troopers although some were used for manual labour (e.g. loading of catapults, movement of Grond and the opening of the Black Gate).
In Edain, the trolls are mainly used in Mordor as tanks which can be upgraded with new weapons for different purposes. The Drummer Trolls are used as unit support. Mollok, the troll chieftain, can also be recruited as a playable hero. In Angmar, the Troll of the North, Rogash, can be summoned with a group of Hill Trolls.