The Fire Lord summoned lava giants and fire elementals from the Firelands to the Molten Core, using them to control and enslave the Dark Iron dwarves.
The Dark Iron dwarves were divided: one faction, led by High Interrogator Gerstahn of Shadowforge, willingly served the Fire Lord; the other, led by Golem Lord Argelmach after Emperor Thaurissan's disappearance, resisted. They outwardly obeyed the fire elementals but didn't fully commit to fighting the black dragons.
It was this resistance that allowed Nefarian to successfully occupy the upper Blackrock Spire before subduing the Blacktooth Grin orcs.
"Thanks to the Thorium Brotherhood, we've contacted the rebels in Shadowforge. They'll help us attack Shadowforge, provided we can resist the Fire Lord and liberate the Dark Iron dwarves!" Galen explained.
After Thaurissan's assassination, the Dark Iron dwarves were leaderless. Without his political skill, the conflict between the submissive and rebellious factions intensified.
The Fire Lord's support of the submissive faction with fire elementals and lava giants put the rebels at a disadvantage. Nefarian's capture of the upper Blackrock Spire offered them a chance to breathe.
Golem Lord Argelmach sought allies. The black dragons were untrustworthy. Submitting to them would blacklist the Dark Iron dwarves with the other dragonflights.
The Thorium Brotherhood's emergence led Golem Lord Argelmach to the Alliance. The two sides allied.
"Tell me your plan," Galen prompted Durin.
"Golem Lord Argelmach suggests using the Hydraxian Waterlords to oppose the Fire Lord. It's the only option the Dark Iron dwarves have found in centuries!"
Where there are fire elements, there are also water, earth, and air elements. These were once the Old Gods' tools, subdued and sealed by the Titans in elemental planes.
The Hydraxian Waterlords, followers of Hydross the Unbound, were ancient water elementals. Ragnaros and Al'Akir destroyed Hydross, and his followers hate fire and air elementals. They would gladly help defeat a Fire Lord fragment.
"We don't need water elementals!" Galen declared.
Halting the Alliance's advance was already a feat. Galen didn't have time to grind reputation with the Hydraxian Waterlords for half a year to obtain the Fire Lord's binding rune.
The Alliance nobles were probably furious.
The daily cost of feeding hundreds of thousands of troops was astronomical. The absence of so many young men from their lands was also a problem. Only Galen's generous grain donations allowed the Alliance to wait even a month.
"Durin, tell Golem Lord Argelmach we've already contacted the Hydraxian Waterlords. Their Duke Hydrossian will help us deal with the Fire Lord once we reach the Molten Core."
"Hiss!"
"Prince, this..."
"Galen, are you lying again!"
"Don't worry, it's fine, Durin. Exaggerate boldly; I'll back you up!"
Duke Hydrossian is the leader of the Hydraxian Waterlords—an ancient secret. Golem Lord Argelmach won't doubt Galen's claim.
As for finding the water elemental army?
Galen glanced slyly at Gandalf.
Gandalf shivered, feeling a chill run down his spine, and tore off several strands of his beard.
"Okay, let's confirm everyone's mission!" Galen interrupted.
"Palthastrasz, take a squad of red dragons to the upper Blackrock Spire to contain the enemy. Don't be too strong or too weak; we don't want to have to rescue you."
"Durin, lead the Mountain Guard and Thorium Sentries to attack the lower Blackrock Spire, drawing the main Dark Iron dwarf force."
"I'll lead a team to sneak into Blackrock Depths and infiltrate the Molten Core from Shadowforge!" Galen remembered that Ophister had used a secret passage to meet Emperor Thaurissan.
"Now for the exciting part: Molten Core speedrun team, strong healer and tank leading the team. Who's in?"
Sylvanas and Alleria were eager to test their new powers from the Storm Altar.
Galen also wanted Gandalf and Aragorn, and brought Medivh and Aegwynn along; this mother and son were powerful combatants.
Galen didn't want anyone else. He felt the Dark Iron dwarf situation was an internal matter.
Among the humans, only Lothar and Daelin were worthy fighters, and they were busy. Turalyon and Uther were still developing.
Besides, Galen felt confident enough to handle this alone!
He requested 300,000 in military funds from the Alliance!
Solving the Fire Lord would help the army enter the Burning Steppes and benefit the war. The Thorium Brotherhood promised to cover half the costs after Shadowforge was liberated. Lothar agreed.
Galen estimated the Fire Lord's strength wouldn't exceed that of the Black Dragonflight. Summoning the kings' power would cost at most a few hundred thousand.