Tower of Trials is a single-player combat mode in Battlesmiths: Blade and Forge where you fight in progressively harder stages and get rewards. Tower of Trials fights usually last one round, and its rewards include some gold and personalized Hero tokens that will allow you to upgrade them in the Barracks or hire new ones for your squad. To see the reward of the current stage interact with the chest in the left part of this floor.
 
Same as in other modes, the amount of heroes you can use at the same time is limited by your Barracks level.