Complex sentence: When she used her formidable skill to infiltrate his Castle she made a startling discovery when she came face to face with the villain, he was her though to be dead father Kentor Omoto.
Split into simpler sentences: When she used her formidable skill to infiltrate his Castle, she made a startling discovery. Upon coming face to face with the villain, he was revealed to be her previously thought dead father, Kentor Omoto.