Holmgang Tournament

From MiddleWiki

A holmgang tournament is a type of armored combat tournament fought within a confined space. The fight is won either by a fighter killing their opponent or forcing them outside of the boundary. Holmgangs are not uncommon in areas where the available fighting space is too small for other options. Many kingdoms structure holmgang tournaments as a variant of a bear-pit tournament though tree tournaments with single- and double-elimination structures are equally as common.

As used historically

A holmgang was a traditional Scandanavian form of combat. Wikipedia maintains an introductory article on the topic.