Hold the line
You may be thinking that Seth was doing a quite splendid job of defending the wall all by himself, never letting even a single Hemogoblin or collared beast slip his stalwart defences. If you were thinking such a thing, you would be wrong. Sorry to break the news to you, but someone had to do it. If you weren't thinking such a thing... well good for you Mr. Wise-guy, what do you want? A medal?
It wasn't inaccurate to say that he was doing a good job, because he certainly was, but he was anything but perfect. With only five defenders on the front line, there were always going to be enemies that managed to slip past, it was just a simple fact of numbers. The battlefield being lit almost exclusively by primitive torches, many of which were steadily dwindling, was not helping in the slightest. With every passing second he was having to deal with more enemies, since the mages were hard at work spawning more from the blood spilled, and had less visible area to work within.