The Emerald Gate — Mark Siegel

Oona and her friends face their ultimate challenge in the final installment of the graphic sci-fi fantasy series that's Star Wars meets Avatar: The Last Airbender!

In the epic conclusion to the 5 Worlds series, the final battle looms as Oona, Jax, and An Tzu travel to the treacherous world of Grimbo (E)! There, Oona must light the last beacon to save the 5 Worlds, but first she has to find it! When Jax saves an old friend, Oona is given a clue to the green beacon's location.
 
Unfortunately, the journey to lighting it on this strange, watery planet is the most dangerous yet. Meanwhile, Stan Moon has one more trick up his sleeve as his frightening powers and mysterious connection to An Tzu continue to grow. How can Oona ever hope to beat him? Can she count on her friends or will a terrible betrayal mean the 5 Worlds will be lost to evil forever?
 
The 5 Worlds series: #1: The Sand Warrior, #2: The Cobalt Prince, #3: The Red Maze, #4: The Amber Anthem, #5: The Emerald Gate