Along with co-participating Misty Mountain Trolls, these were very large, dwarfing all the others seen previously, (about 25 feet tall or more) more importantly they were either fully or partially armored, unlike the smaller yet extremely similar Guldur Olog-Hai, which were fully armored but as stated above much smaller. These trolls were fearsome weapons on the field and devastated dozens of soldiers with one strike alone of their weapons.
These trolls were quite intelligent and kept formation with the orcs as they marched to battle, in battle these trolls carried bladed axe/sword like weapons upon their arms, (similar to the Guldur Orcs' shields) long metal maces which could smash the very earth several feet into the air, taking down several men at once. Some even used their bare hands, balling them up into fists to smash the allied armies, or sweeping them up and throwing them like rag-dolls.
The less fortunate of these trolls were also hideously amputated by the orcs, giving them morning star (wrecking ball-like) arms in place of their flesh and blood ones, some had metal hooks placed into their backs for goblins to take hold of, and the most unfortunate was blinded and given reigns dangling from their eye sockets for orcs to directly take control of.
Unlike the smaller Guldur Olog-Hai, these trolls couldn't simply be taken down by a spear throw to the neck or a few arrows. It would take dozens of arrows and several spears/pikes to be sent into the unarmored parts of the trolls in order to take them down. A premeditated attack upon a troll would usually work and need to be planned out well in order to take out the beast before it took down a whole garrison.
In the great battle outside the dwarf-city of Erebor, Azog's invasion army included five of these massive trolls, including two amputated war trolls. While two of these trolls wore armor and carried long metal maces on their arms as weapons against the dwarves, elves, and men, a third troll wore little or no armor and carried a huge spiked club. The last two trolls, which were amputated war trolls, had morning-star arms and spiked clubs for their legs and feet.
During the Battle of the Five Armies (Extended Edition only), an unfortunate war troll was commandeered by Bofur, using the chains connected to its eye sockets to move it around. He used it to fight against the Guldur Orcs, until the other dwarves use a dwarven battle cart and use it to smash through the army to get to Azog. Bofur follows them with his war troll until another war troll comes across the other dwarves. Bofur controls his war troll to fight the other war troll. The weight of the other war troll causes it to sink into the ice. Bofur and his troll begin to sink as well, until Bofur kills the other war troll with his. Bofur abandons his war troll and goes with the others, while the war troll wanders off aimlessly, smashing into things. It eventually comes across Legolas, who is shooting on top of a tower. The troll beings smashing the tower, until it rams into it head-on, then falls over the edge into a chasm below, killing it.