Mirilass is the commander of Lord Harke's forces, and appears in the Elwin and Shaera campaign in Heroes of Might and Magic IV.
Lord Harke told Mirilass to lead Elwin into the forest and slit his throat, so that Harke would have Shaera to himself. As Mirilass didn't want Elwin's death on his conscience, he instead led Elwin to a secluded glen, and told him to remain there for the rest of his days - if he tried to leave, Mirilass's rangers would kill him. With the aid of his white tiger friends, Elwin still managed to escape.
As Elwin needed Mirilass to prove to the Elven Court that the elf's forces had attacked him, not the other way around, Elwin hunted him, but Mirilass made his way back to Lord Harke's lands. But as he couldn't face his employer without losing his life, Mirilass hid in the woods.
As Elwin couldn't find the elf if he didn't want to be found, he instead travelled to the town of Splitoak, where Mirilass's brother lived. He told Elwin that Mirilass was hiding next to a blue keymaster's tent.
When Elwin found Mirilass, the once-proud elf was drunk and muttering, torn between his loyalty to Harke and his morals. Hoping to die in battle, he drew his sword and attacked Elwin's forces, but Elwin captured him alive and told him to write a letter to the Elven Court, explaining the truth about Harke's and Elwin's rivalry. Elwin sent Mirilass to Splitoak to be with his brother while Elwin invaded Harke Manor, freeing Shaera.
Elwin describes Mirilass as "a stiff elf", and his brother as "a lean, older elf with the same stern features I remember belonging to Mirilass".
