Along with co-participating Misty Mountain Trolls, these Trolls 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. 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, these trolls carried bladed axe/sword like weapons upon their arms, (similar to the Guldur Orcs' shields) and long metal maces which could smash 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.
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 ones, some had metal hooks placed into their backs for Orcs 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 troll in order to take it down. A premeditated attack upon a troll would usually work and needed to be planned out well in order to kill the creature.
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 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), a 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 procured a dwarven battle cart and used it to smash through the army to get to Azog. Bofur followed them with his war troll until another war troll came across the other dwarves. Bofur controled his war troll to fight another 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 using the one he is currently controlling. 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 begins smashing the tower, until Legolas drops onto its head, sword in hand, mortally wounding it. The creature then smashes into the tower head-on, falling over the edge into a chasm below, killing it.