Complex sentence: Before arriving, however, the three companions must walk the Paths of the Dead in an effort to convince the Army of the Dead to join their cause in the War of the Ring, by defeating the King of the Dead (Jarion Monroe) in combat.
Split into simpler sentences: Before arriving, however, the three companions must walk the Paths of the Dead in an effort to convince the Army of the Dead to join their cause in the War of the Ring. To do so, they must defeat the King of the Dead (Jarion Monroe) in combat.