Trolls are the rarely seen, extremely heavy infantry of the Empire of Night. They are never used for garrison, but are reserved for assaults against the heaviest defenses of the Dwarven Safeholds and other persistent enemies of the Emperor.
The Resistance knows little of trolls. They are rumored to be tall, strong, and stupid. They have green skins and are supposed to nigh-unkillable unless burnt by fire or acid.