Steam units are an enemy-only physical calvary enemy that are exclusive to Fire Emblem Heroes. The foot soldiers of Niðavellir, these seiðjárn-powered units utilize generic versions of the seiðjárn mounts designed for Niðavellir royalty. These units have the ability to wield swords, lances, or axes, and always have Gullinbursti equipped, a skill that enables Canto. In game, they're referred to as a steam version of their weapon type, such as Steam Sword or Steam Axe.
- Steam units are the first generic enemy type in Heroes to not use the aesthetic of the Emblian Empire.