Húsbrennur

Your Infantry units gain Battering 1 (melee). When your Infantry units attack a building that has an enemy unit on the same square or garrisoned inside, that unit takes 2 true damage.

Meaning “house burning,” the Norsemen didn’t use known siege engines, but they did use fire to destroy buildings while minimizing casualties among their own ranks. A person trapped inside their burning house would die within minutes.