"This can't be good," Robin says as he charges up the stairs, as fast as the big man can, which isn't too fast.  He pulls out his shotgun, thinking the entire time, please let it be slug, please let it be slug.  When the beast comes into view he levels the barrel and yells at it, drawing it attention away from the girls.  When it turns to look at him he pulls the trigger.  Charging the gun he fires again.  He continues until all nine rounds are fired.  His actions were automatic and he knows he hit it, he just hopes its enough.