When you fight the huge freaking spider, shock it when it curls up to attack, then run in and whack it with your axe. She'll retreat to the web behind her and send out the medium spiders...kill them, she'll come out again and launch the babies. Ground shake them, rinse, repeat.
Then you have to make it back to the Kill Master within 1:30. I did it with 20 seconds to spare, and I screwed up once, so it's pretty simple.