Rusty is lucky: the crystal turns out to be fragile and shatters into pieces from the explosion. As soon as it is destroyed, the ratlings and ice goblins lose interest in people and scatter in all directions.
"Whew, that was close," said Swordsman 3, wiping sweat from his brow. "And you really throw bombs well, Rusty."
"Too bad about the first one..."
The quest has been completed. You can return to the settlement.