Quick-take: The series has become formulaic.
I am torn about this one.
Lets start with the title: Catacombs. Richtor never actually makes it into the Catacombs. That's the least of my concerns. We already spent a book inside the Catacombs. The main story arc is him and a crew going on a few hunting parties. The first gets badly injured. This happens after he self-reflects about neglecting his village duties... which he spends ~2 hours on before fighting a tentacle monster and deciding to throw a big party. Then back to hunting trips. Another legendary object is acquired. Levels are increased. Unneeded cliffhanger setup. End book. The forced cliffhanger from the previous book was not even fully resolved. It was simply tabled for another day.
In the middle, this book went off rails. Richtor gets drunk during his party and then wakes up next to "a beautiful elf druid" with no consequences. After the book describes her nude appearance, she just winks at him and sashays away. Another part of the story he falls into a pit and lands in a bedroom with 3 well known female movie stars... they are nude... and 10 feet tall for some odd reason. The book explains it, but... sure, whatever.
I think Aleron Kong is just punking us. He struck gold with the first novel and is milking the series to see how absurd it can get before we all walk away. Once again, there was no meaningful story progression and he forces another massive cliffhanger. The books are becoming very formulaic, which was my concern/prediction from the previous book.
Despite my frustrations and increasing absurdity, the book was entertaining. That is goal #1 when I read SFF, so I've picked up Book 5. I'm giving the series a chance to get back on track.
Score: 3/5. Dr. Kong, please start closing some story arcs.