Please help!I cant´t find the Serpent Key. I have attacked kreug from far away at the temple entrance, with the comet spell and i can´t take the key. It´s bug!? At the Wizard or Warrior path i had the same problem. I only found
one kristall for the wizard path.I had kill one of them with a wizard spell from distance.

These are NOT bugs.

As far as choosing one of the paths; once you choose one crystal the other is no longer avaiable. That is the way the game was designed.

If you are referring to the snake priest at the entrance to the temple, I don't understand why you attacked him. He is not hostile and will give you a key as well as some background information. There are consequences to your actions. If you attack people who are not hostile, you may find that you have difficulties completing certain quests.