The arcanium smelter is straight ahead. Well clear the dwarves from the smelters area. On the right side is a lever. It will shut down the fire that is killing slugs. Push the lever.
Going past the slugs and up the ramp, go right at the passage. Follow this platform to the end. Go down the stairs.
Follow this walkway until you can go right. Have your minions break the barricade.
As you walk down the ramp a cut scene will begin of the Mama Slug.
Kill the Mama Slug and all the baby slugs will stop coming out of the holes.
Go around the mines and clean up any slugs. Once that is done have your red minions grab the smelter.
Go back to where you passed all the fire. This time take the left passage.
There will be only fire beetles on the path. Follow this path around and to the right. When you get the circular path, take the path that leads to the left.
Follow this path until its end. There will be a tower object here. It is the third level fireball spell upgrade. Have your minions grab it.
Now to get the tower objects past the fires. Go back to where you crossed to go kill the mama slug. Going from the left to the right. Flip the first switch to the left with a minion.
When the first object crosses the grill flip the switch back to the right. Then flip this switch back to the left one more time.
Go over to the second switch. Flip this switch to the right. The minions with the first object will cross. Then flip the switch to the left.
Go back to the tower. Make new armor and weapons. When done making new equipment, go to the tower heart and select Golden Hills pass. Go down to the fortress. Some dwarves with the bombs may have respawned.
Kill the dwarves with your minions. Go through the doors to the left. Down the stairs and hang a right. Go straight and up the stairs.
At the top of the stairs, go left across the bridge.
On the other side of the bridge, go to the left. Follow this walkway until you get to a door to the right. Go through door. A cut scene will begin. Continue down the path.