Complex sentence: Prior to his death, the elderly "vladika" had dictated his will and testament to Njegoš's old mentor, Milutinović, where he named Njegoš as his successor and granted all of his ecclesiastical and secular powers to him.
Split into simpler sentences: Prior to his death, the elderly "vladika" had dictated his will and testament to Njegoš's old mentor, Milutinović. The "vladika" named Njegoš as his successor and granted all of his ecclesiastical and secular powers to him.