Complex sentence: The High Council is floundering, the population is restless, the monks are getting excited about an ancient prophecy they have discovered and so the player characters are assembled to restore the Celtic kingdom of Pellham to its former glory.
Split into simpler sentences: The High Council is floundering, the population is restless, and the monks are getting excited about an ancient prophecy they have discovered. The player characters are assembled to restore the Celtic kingdom of Pellham to its former glory.