Complex sentence: Karlson also warns her that the curse follows any part of it, explaining how earlier the family dog had become afflicted by the curse after eating Kent's clown "nose"; which forced him to kill it.
Split into simpler sentences: Karlson also warns her, that the curse follows any part of it. Earlier, explaining that the family dog had become afflicted by the curse after eating Kent's clown "nose"; which forced him to kill it.