Complex sentence: The monkey is found by children, unknowing that their father was tormented by the monkey, which seemingly comes into motion on its own predicting the death of someone, years before when it worked its lethal magic on his family and friends.
Split into simpler sentences: The monkey is found by children, unknowing that their father was tormented by the monkey. It comes into motion, seemingly on its own, predicting the death of a person, years before when it worked its lethal magic on his family and friends.