The Unwanteds #7:Island of Dragons by Lisa McMann

My name is Aaron, and I know I must leave Artime soon. My twin brother Alex and his friends seem to have forgiven me despite all the evil I've done in the past, but I don't understand how to live among kindness. I can sense that Alex is jealous of my magical abilities, but he doesn't know about the mistakes I've made. We've discovered pirates have been traveling to Warbler Island, and that can only mean trouble. The queen is determined to retrieve the prisoners we helped escape, so we're now preparing for an attack. But Alex just told me a disturbing secret. He gave me a medicine that makes me immortal; I can't be killed. He also asked me to become Head Mage of Artime, but my deep thirst for power is starting to consume me. I don't know if I can control it.

This book is the last one in the series, and you really need to read the others first. It has a lot more happening than some of the earlier books, as Artime prepares for war. Actually, the battle itself takes up much of the plot, since it goes on for days. Alex is unaware of his brother's hidden demons, so allowing him to become Head Mage could be disastrous. Aaron's internal conflicts become major issues, and the truth eventually come out. The author does a wonderful job of bringing the series to an end, although there are some parts that may upset readers. War is destructive, and some main characters are killed or suffer serious injuries that can't be healed. I've been reading this series for five years as it was written which creates some problems for me. Many, many characters have been introduced during the series, some of them people but many of them magically-created creatures. Waiting a year for books to be written sometimes makes it hard to remember all of the characters' personalities and relationships. However, you shouldn't have that problem if you're just starting the series. Since I read all seven books, I can obviously recommend the series.