Kai read all the information he had about the Warlocks and how to become one. Apparently, the process was quite simple. All one needed to do was get the blood from a powerful beast, and then do a blood transfusion.
The other part of the class changing was to say a few incantations, which were described in the scroll.
Out of all the things, getting a powerful bloodline to do the transfusion was the hardest part. Rebrum wrote on the scroll that changing the bloodline was still something he didn't know how to do, so it was important to get a good one from the start.
The idea of turning into a Warlock drew Kai's attention, but he still didn't know for sure if he would follow that path. The information about it was just too limited for his own tastes.