So instead of letting the crops rot in the fields, young Karl moved in.
To get rid of the intruder, the Slags, who were not a violent people by nature, came up with the ghost idea, smearing themselves with glowing fungus.
It is unknown whether the Chosen One helped establish good relations between Modoc and the Slags, the people of Modoc continued to consider the place haunted or simply wiped out the Slags in what they considered revenge for Karl's supposed death, since nothing on the matter is mentioned by the narrator in the endgame cutscene.
They also cannot stand the bright light of the sun, as living underground for so long has devolved their eyes to a form of intense permanent light sensitivity.
In many smelting processes, oxides are introduced to control the slag chemistry, assisting in the removal of impurities and protecting the furnace refractory lining from excessive wear. A good example is steelmaking slag: quicklime and magnesite are introduced for refractory protection, neutralising the alumina and silica separated from the metal, and assist in the removal of sulfur and phosphorus from the steel.
Slag run-off from one of the open hearth furnaces of a steel mill, Republic Steel, Youngstown, Ohio, November 1941.
The smelting of copper and lead in non-ferrous smelting, for instance, is designed to remove the iron and silica that often occurs with those ores, and separates them as iron-silicate-based slags.
Slag from steel mills in ferrous smelting, on the other hand, is designed to minimize iron loss and so mainly contains oxides of calcium, silicon, magnesium, and aluminium.