Darius felt pity for the Dark Horse that had actually tried to challenge Gunner's might in one-on-one combat. Even he didn't dare to challenge his Branded Servant despite possessing better stats in that regard.
With his Earth's Guardian skill active, Gunner basically had the Strength, Endurance, and Damage/Defense of a mid-stage Journeyman. Against these early-stage Journeyman undead, he was no different from a bully.
Darius blinked to other parts of the battlefield and rained his Sparks down on foes. He had already warned his two undead Liches to conserve as many minions as they could, since there were very few living enemies for them to use as replenishment for their forces.
Wasting them all on mere Journeymen was foolish, yet Darius also needed them to level up.
The upgrade from Skeleton Warriors to Liches might have given them much better skills and abilities, but it had also taken away a large part of their prior offensive power.