Complex sentence: In "Dead Things" Warren hypnotizes his former girlfriend Katrina to be his sex slave, and kills her when she shakes off his control; the Trio then use time-distorting demons to convince Buffy that she killed Katrina.
Split into simpler sentences: In "Dead Things" Warren hypnotizes his former girlfriend Katrina to be his sex slave, and kills her when she shakes off his control. The Trio then use time-distorting demons to convince Buffy that she killed Katrina.