Complex sentence: Then Vakama frees himself and tells the Shadowed One that Makuta was the one to kill Nidhiki and Krekka, after which the pair of powerful monsters begin their fight.
Split into simpler sentences: Then Vakama frees himself and tells the Shadowed One that Makuta was the one to kill Nidhiki and Krekka. Afterwhich, the pair of powerful monsters begin their fight.