Complex sentence: It was then that Hori realized after the father of the family informed him of Silvergon's weakness and informed Tiga, who then used the monster's weakness against it to destroy it.
Split into simpler sentences: It was then that Hori realized after the father of the family informed him of Silvergon's weakness. Hori informed Tiga of this, who then used the monster's weakness against it to destroy it.