Complex sentence: Dracula also feeds Mina his blood, dooming her to become a vampire should she die, afterwards killing Renfield and destroying all of the copies of their, except for one which Dr. Seward kept in a safe.
Split into simpler sentences: Dracula also feeds Mina his blood, dooming her to become a vampire should she die. Afterwards, he kills Renfield and destroys all of the copies of their except for one, which Dr. Seward kept in a safe.