Darion's aim coming into this hunt with Seren wasn't to engage in fights that would lead to a shortage of man power, undead power, in Darion's case, because his undeads weren't humans.
They were tools, weapons, assets that he had spent weeks collecting and raising.
Every single one of them represented effort, time, and the careful work of unearthing graves and speaking the words of revival. Losing them wasn't just a tactical setback. It was a waste of everything he had put into building his army.
When he faced Valdenmoor, a proper war, he lost a lot of knights. Half of his knights during the first invasion, when they were vulnerable and unprepared.
Even during their assault on Valdenmoor, when they had Vera's magic equipment to help out, he still lost undeads. But that was a war. His aim was to win, and winning in that sense came with losses, large, casual, or very little, it was expected to at least lose something.
