The Tale of Igor's Campaign

Maybe, but even if that's the case, such subtleties aren't particularly important to the Orcs. However, it seems to me that they added this idea to the lore after the fifth installment of *Heroes*. The original premise, if I'm not mistaken, was that the Griffin Heart couldn't kill Inferno creatures. And this was associated with many problems: both that Nicholas didn't really defeat anyone, and that Biaara was able to escape because of it... But the idea of resurrecting Urgash is less obvious. At worst, one could even assume that Urgash doesn't resurrect everyone, but only his most distinguished followers.