SOLVED. YA Fantasy. Kids go underground to compete in an arena with their magic tiles. [s]

[Breann]

Ok my son read this book in 2019. Cant remember the name or the author. The book starts out with a Dad telling his son to deliver a letter to a man. The Dad's dog will guide him there, and do not open the letter. Dog leads him through the forest to a big tree with mechanical pipes sticking out, and they go in a secret entrance. He goes down and gives the letter to a man, who asks if he opened it. He says yes, the letter from his Dad says "I think it's time for him". Two more kids appear and the man puts them in a cart, and they go down a railway. They pass bats and stop at a desk with a girl behind it who gives them each a bag. The boys Dad's apprentice shows up and takes the kids to the boys Dad. His Dad has them all dive into a pond and grab a special tile that gives them powers. After they all get their tiles, the boys dad shows them to their rooms and their rooms are like they are camping outside. The kids compete in an arena against another team. The winning team gets sand dollars, which is the currency down there. My son says the dogs eye glow blue, and when he is happy they get brighter. He also remembers the bats in the railway making the kids forget everything they learned underground so they don't tell people what they know, and the bats also make them remember when they come back.

In the second book, one of the worlds is volcanic. Something bad is happening in this world and its making the volcanoes in the real world erupt more than usual. It is spreading ash all over New York. They go in and figure out whats going on, and save that world. They are also trying to find the boys dad because he went in there and got lost.

The cover of the second book is blueish with 3 kids standing on top of a cliff above a pond. There are stone pillars that are holding the ceiling up.

This is all he can remember, any help would be great! Thanks!

[Librarian Jessie]

Could it be the Balance Keepers Series by Lindsay Cummings? The first book is called The Fires of Calderon, & the second book looks exactly how you described with the title, The Pillars of Ponderay.

[Breann]

Omg YES!!!!! THATS IT!!!! Thank you so much!!! We literally stood in Barnes and Noble for 45 minutes yesterday describing what he could to the poor lady who couldn’t find it lol. Thank you!!!

[Kris]

Glad you found your book, Breann. Here's the link for Jessica's find - the first book in the series: The Fires of Calderon by Lindsay Cummings.