Complex sentence: While being closely watched by Thomasin, Samuel vanishes, kidnapped by a witch in the woods, who kills him and uses his blood and fat to make a topical ointment for her body.
Split into simpler sentences: While being closely watched by Thomasin, Samuel mysteriously vanishes from her presence. It is then revealed that Samuel was kidnapped by a witch living in the woods, who kills him and uses his blood and fat to make a topical ointment for her body.