This was a book that was free on Amazon Kindle just a few years back. Lost my account and, subsequently, access to this book.
The book is about a kid named Tan who slowly learns that he can talk to or use the different elements. (Earth, Water, Fire, Air, and eventually Spirit)
There's a woman that Tan has to save who has the ability to use/talk to spirit.
The enemies were these beings consumed by fire. At some point, Tan struggles with being consumed by fire.
The climax of the story has the character Tan climbing in a pool that was protected by all four elements. That's where he first hears the element of spirit I think.
There are also dragons who were the first to use the elements. That is how Tan communicates with them, through the element of fire.