To Raynor's horror, Withered Heath was a region that lied in the east of the Grey Mountains and was feared to be breeding grounds of dragons which hated the dwarves for many years. Sauron had the Mouth of Sauron to seek an alliance with the dragons against the dwarves. "We must earn favor from the Dragons here, destroy any Dwarf settlements you encounter," said an orc.

The Dark Voice had sent Mutalisks and Corruptors to provide air support for the Mordor army. The Mordor army this time had siege engines and attack trolls for the assault. "The Dwarves are capturing the dragons when they're still young. These Drakes can be very powerful, free any Drake they've captured, and they will join us against the dwarves," said an orc as there were enclosures holding young flightless dragons. There were pike-wielding dwarven phalanxes patrolling the enclosure. The Mutalisks quickly laid waste to the phalanxes so that the orcs could bring down the walls with the battering ram. The orc warriors were a match against the dwarven phalanxes and the orc archers picked them off from a distance. The orc warriors first engaged the dwarven warriors and the orc archers took them out with ease.

"These drakes are powerful allies, wipe out the Dwarves," said the Mouth of Sauron. The combined forces of Zerg, hybrid, and Mordor army launched the assault on the northern settlement. The Corruptors first covered the axe towers with slime preventing them from launching axes enabling the Mutalisks to use glaive wurms to easily destroy the long-range catapults that fire two projectiles simultaneously. The attack trolls were lethal against the dwarven warriors and could destroy buildings. Despite the dwarven catapults could kill Hydralisks along with inflicting damage on Roaches and Protoss-based hybrids; the Zerglings, the Zerg-based hybrids, and attack trolls could destroy those dwarven long-range siege engines. After the drakes in the north were freed, the combined forces headed east.

The Corruptors first covered the axe towers with slime so that the Mutalisks could take down the catapults enabling the orcs to bring down the gate with battering ram. The dwarven axe-throwers could not do much damage to the Corruptors and the Mutalisks were agile to dodge those projectiles, however they managed to slay a few Zerglings. The Zerg-based hybrids drew the dwarves' attention so that the axe throwers could hurl at them and the axes did not do much damage to those monsters. The dwarven phalanxes and warriors skewered and hacked a few Zerglings. The drakes easily caught the dwarven warriors and phalanxes on flames causing them to run around then collapsed to the ground motionlessly along with torching the structures. The Hydralisks and Roaches shot and corroded the dwarven axe throwers respectively. When the drakes were in range, the dwarven axe throwers did not a stand a chance. "These … dragons are impressive. We will be unstoppable," the Dark Voice commented.

After the combined forces destroyed the dwarven settlements and freed the last two groups of drakes; "all the Drakes are freed, bring them to the Dragon Lord," an orc ordered. A group of dwarven battlewagons stood in their way; nevertheless the Zerg-based hybrids, Mutalisks, Roaches, and attack trolls took them down. "The Men of Dale are guarding the path to the Dragon Lord's lair," said an orc. The Men of Dale were archers with a longer attack range than dwarven axe throwers; however they were no match for the Zerg-based hybrids, drakes, Roaches, and Hydralisks. Eventually the path was secured with the men shot, incinerated, slashed, and corroded.

"I bid thee fair tidings. I wish to treat with thee on behalf of Sauron the Great," the Mouth of Sauron enlisted the Dragon Lord that was an armored dragon to help route the dwarves out of Erebor and rid them of their king. The mountain fortress would be given as a prize and the time had come for dragons to fight for Sauron and his allies.

Raynor then watched the combined forces of the Dark Voice's and Sauron's invaded the Lonely Mountain. "Before assaulting the mountain, we will first conquer the city of Dale," said an orc.

"As it is like a Terran city, best that we infest it," said the Dark Voice. As the invasion was full scale, the Zerg Ultralisks and Brood Lords were used to cover the Infestors that placed Virophages. The Zerg structures Raynor had not seen before spread the Zerg virus infesting the man-made buildings in order for infested Terrans to spawn. The Brood Lords could outrange the defense towers and destroyed them along with the Men of Dale inside. The Mouth of Sauron was pleased seeing the whole city converted into breeding grounds for infested Terrans that were limited to the ones unarmed and the larger ones resembled centaurs. The dwarven phalanxes had difficulty stopping the centaur-like creatures and were no match to the infested Terrans. However, the infested Terrans were easy targets to dwarven axe throwers and men of Dale. None of the dwarven troops and the men of Dale could stand against the Brood Lords. "Dwarves, fall back and protect your king," said the human leader who appeared similar to Bain son of Bard. The man gave his own life as a Brood Lord managed to tear him to shreds.

"Dwarves are attacking from the south," said an orc as battalions of dwarves arrived along with their leader.

"It's the fool Dain, he must have rallied the Dwarves of the Iron Hills," said the Mouth of Sauron.

The Ultralisks were lethal against the dwarven warriors, axe throwers, and catapults as they sliced battalions of dwarves into pieces using their Kaiser Blades. "I wonder where you buggers come from," Dain spoke as he hacked several Zerglings, however an Ultralisk cut him to shreds.

The Zerg flyers could not enter into the mountain leaving the Zerg ground forces and the hybrids to enter in flanks. Sauron was ready for the attack on the Lonely Mountain as Easterlings, Corsairs as infantry, along with Haradrim on foot and on Mumakils participated in the assault. The orcs manned the battering ram brought down the gate with the Dragon Lord storming in.

"Dwarves of the Mountain, remember this day or we will fall to the hands of the wretched fiends of Mordor," it was Fili who appeared to be older. Raynor also saw the other former traveling companions of Thorin Oakenshield had grown older: Dwalin, Nori, Kili, Bifur, and Bofur. Balin, Oin, Ori, Dori, and Bombur were missing. Tauriel was the Wood elf who fell in love with Kili and was present during the fight. The Easterlings stopped the dwarven battlewagons on their tracks, the Corsairs stabbed the dwarven phalanxes, the Haradrim picked off the dwarven warriors and phalanxes. The Mumakils charged to crush the dwarven axe throwers and used their tusks to destroy battlewagons. The Dragon Lord caught every dwarven troop on fire causing them to run around and collapsed to the ground motionlessly. Tauriel and Kili picked off the orc and Haradrim archers. The other dwarf heroes hacked and slashed the orcs, Easterlings, and Corsairs.

"I wish Jim is here," said Bofur as the Zerg, hybrids, and infested Terrans joined the fight. The Ultralisks were also lethal against the battlewagons and the phalanxes could not stop them. The dwarves found themselves slashed, sliced, shot, and corroded by the Zerg, hybrids, and infested Terrans. Despite the heroes' efforts; Raynor was horrified to see the dwarf and elf lovers were shot dead by Hydralisks, Dwalin was corroded by Roaches, Fili was mauled by Zerglings, Bofur and Bifur were sliced by an Ultralisk.

"King Fili is dead, Sauron will be pleased with the news," said the Mouth of Sauron and the combined forces destroyed the Throne of Erebor.

It was worse than the day Smaug the dragon seized Erebor for his own as the combined forces of Mordor, Zerg, hybrids, and infested Terrans purged the dwarves of Erebor.