Shadow Kingdoms: Riftlands – Worth It for Solo Gamers?

About Shadow Kingdoms of Valeria: Riftlands, from BoardGameGeek:

A new shrine in the Monster-kin cavern has been discovered. Three magical rift gates in the shrine open onto Valeria castles rich in plunder and ripe for attack. You'll discover ancient relics to give your armies unique powers and as your collection of powerful talismans grows, so too does your desire to become the next General of the Shadow Kingdoms. Riftlands introduces two powerful and thematic asymmetrical powers for each monster-kin race. One is active at the start of the game and the other can be unlocked when you complete a Battle Plan. A new set-collection mechanic is added to Shadow Kingdoms through the 30 Relic cards you can acquire in the Riftlands, and each relic also has a unique power to further the player asymmetries. An additional 15 new Champion cards are also added to leverage the new mechanics and ideas presented in the Riftlands expansion. -description from the publisher