It takes Dorgath a while (the rest of the turn, Dorgath's Lifestone of Ashraz heals him of one more Wound, up to 14/15) to secure the rope to one of the posts on the near side of the bridge. The post seems immovable, but Throg stands nearby, ready to grab the rope if anything happens...
Dorgath slips on the bridge and dangles into the flames (Dorgath sustains 4 damage) but makes it to the other side. As soon as he does, six giant rats and twelve giant bats emerge from the shadows, ambushing him.