Into the Temple

After Drillk's memory returned, he told me how to obtain the keystone. It's locked away in the Temple of Sul.

Quick walkthrough

 * 1) Break the Ward Blocking the Temple of Sul
 * 2) Enter the Temple of Sul
 * 3) Search the Temple of Sul
 * 4) Hints: Solve the Puzzle

Walkthrough
To enter the temple, select the option "Betrux"