Sulfurina
Sulfurina is the embodiment of the Emerald Green Spring, a hot spring notorious for emitting a toxic gas mixture of hydrogen sulfide and sulfur dioxide. The group encounters Sulfurina while attempting to retrieve sulfuric acid from the spring—a crucial ingredient needed to synthesize aspirin for curing Ruri's illness.
The spring itself is hazardous to navigate due to its poisonous emissions. Silver serves as a practical detection tool, reacting to hydrogen sulfide and allowing the group to identify where the toxic gas is concentrated so they can safely chart a path through the area.
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