Named after the tempestuous alliance of the Kingdom of the Twelve Mountains, Twelve Mountain's War was a game of odds and bluffing. Typically using cards but also playable with dice, it was an especially popular tavern game across all of Somnum.
Drawing from a specialized deck (or rolling at random), one person would start as the "High King" and acted as that round's dealer. Each participant would place an opening bet, typically with a maximum agreed-upon before the game, then drew five cards (or rolled five twelve-sided die) in secret.
Starting to the left of the High King and continuing clockwise, each participant would reveal one of their cards (or die rolls). This step was then repeated twice more; on the second and third round, each participant could raise their bet before revealing their number. The other participants each had three options: match the bet, raise their bet (in which case all participants had to match that bet in turn), or fold, forfeiting any bet they placed and dropping out of the round.
Each participant who did not fold then revealed their card totals (or die roll totals) in the open, and the player with the highest total won the pot. The winner then became the High King for the next game, assuming play continued.