Currently the PCs are heading back towards a hostile Orcish city in an attempts to return to their ship and escape the area. But the city is about to be attacked by an army of Giants, led by one who is carrying a McGuffin they've been interested in. I've planned out a good climax if they go to fight off the Giants, killing their leader and saving the city and such.
But I want to have an idea for if the PCs decide to try and actively avoid the fighting, sneaking through the attacked city in order to get out in the confusion. I don't want to just move the Giant general fight to the PCs if they attempt to go around the battle, but I still feel like I want some kind of big fight to end the story arc.
Any ideas? What kind of big fight do you have for a group of low-paragon characters who are trying to return to their ship in the harbor outside a city under siege? (the city is being attack from land, so away from the harbor)