During the time William was away meeting the leaders of different forces, Stark was fighting desperately and bravely with thousands of high-end masters.
They were doing a great job actually. Any one of these masters was enough to shake an entire city or battlefield. The only problem was that their foes weren't that easy to handle and weren't normal at all.
Monsters received all the attacks and didn't flinch. The most they showed was for them to retreat a few steps back with every violent explosion. Stark and others weren't trying to kill these hounds but buying time for the masters in the city to run safely away.
But when they heard the loud cheers and shouts coming from the walls, heard the defying words and tone of the masters there, refusing to leave and run away, they felt their blood boil.