The Overpass Is in Front of the Overpass and You Hear a Loud Racket Coming From Behind the Overpass

So you have this one goblin on the overpass and after his word of warning nobody's really rushed to his aid either by the two entrances the overpass connects or from the depths of the cave that you're facing. You hear a pretty terrible sound coming from down there and top of the order is Magnus so I am gonna hole up in that, he says. So go ahead and roll initiative okay?