Lost Ruins of Arnak was a surprise hit for me and my son. This expansion adds more variety in all possible ways (items, monsters, locations, helpers, etc) but the biggest addition are the leaders. Instead of everyone starting the same, each leader provides assymmetry through custom starting decks and powers. Highly recommended!
Really interesting and fun game that is quite different from anything else I own. Draw abstract(ish) tiles one at a time and place them facedown on a grid, using them to collectively develop a story. Then, see if you can remember the story and where each tile was placed. It sounds impossible but it works! Great fun.