Complex sentence: He lives a peaceful life with his childhood friend Mina Hakuba until he is drawn into Dracula's castle, where he discovers his dark power, the "power of dominance," or the ability to absorb the souls of his defeated enemies and use their abilities.
Split into simpler sentences: He lives a peaceful life with his childhood friend Mina Hakuba until he is drawn into Dracula's castle. Once there, he discovers his dark power, the "power of dominance," or the ability to absorb the souls of his defeated enemies and use their abilities.