Volume 1 Book 15 starts by speaking with Elrond and is all solo-able up until Chapter 12. In Book 15 Chapter 12: One hope remains, you must protect Amarthiel/Narmeleth and defeat two bosses Mordrambor and Mordirith. The second Boss is easy but for the first one you need a good strategy.
If you have a problem to defeat Mordrambor read our guide
