Karn vs Shadehawk?

Actually, Warbringer was shown to have enough attack power to do 9999 damage, but not break the damage limit. While heroes universally have at most 9999 HP (Lance excepted), major villains tend to have more than that. Argent's HP numbered several times that at LEAST, and quite possibly an order of magnitude larger.

...Oh wait, it was a cutscene! Well, in that case, nothing is impossible... if it can be contrived.