[quote=@Zelosse]
I imagine the coffins are hard to scale, and our brittle enemies will find it difficult to climb the relatively smooth surface. So maybe it buys a few seconds, but it does its job of funneling the monsters to either side instead of head on... right?
[/quote]

Yeah, that's about the thick of it. I mean, other than that, there's only so much surface area sekeltons can scale on those coffins. So it would only be about one or two making it to the top at a time, every minute or so.