No spider boss showed up for me?

[Drakasun]

Hi
I remember finding a cave somewhere and going inside and it looked like a giant spider's lair, but it was just empty, there was no spider and I haven't had a quest which led me to a spider as far as I can remember. I am now at the stage of having all the stones and searching for the circle which I also can't find. How did I miss the spider, did I miss a whole section of the game somehow?