Complex sentence: In "Rodrick Rules", Scotty was going to do a magic act in the Talent Show with Rowley as his assistant, but after Greg breaks Rowley's big toe, Greg has to fill in for Rowley.
Split into simpler sentences: In "Rodrick Rules", Scotty was going to do a magic act in the Talent Show with Rowley as his assistant. But after Greg breaks Rowley's big toe, he has to fill in for Rowley.