The only thing that saves her is the shield, and a lot of training. Its more reflexes than anything when she partly blocks the hit, though the fist still drives her back off her feet and sends her skidding through the sand.
Still, there's a city depending on her, and, so far as she can tell, no one else in the way. She ignores the pain, pushing it back, and flings the hammer - then flies right after it, trying to deliver her own impact right after the hammer collides with the behemoth.