Wit'ch Gate (The Banned and the Banished #4)

In a spectacular feat of daring and magic, Elena and her army of outlaws and rebels have defeated evil's minions and released the mystic secrets of the Blood Diary. But the malevolent Dark Lord has unleashed the Weirgates—black wells of ferocious energy that are his greatest source of power. Now Elena's bravest allies are sent to find and destroy the Gates, as windships carry the fight north to the frigid woodlands, south to the burning desert sands, and east to the blasted regions of dread Gul'gotha.

Along the way, they will face their own personal demons as well. The twin brothers Mogweed and Fardale race against time to break the curse that has stolen their shape-changing birthright, and Elena's brother Joach must evade the desert sandsharks if he is to master his own elemental power. The trail will lead them even to the fabulous el'vin homeland of Stormhaven. None of the rebels will come back unscathed, some never returning at all...

And Elena herself must journey to Gul'gotha. Daring the enemy's own lair, she must emerge victorious if she is to reveal the secret of the Dark Lord's frightening identity—and the shocking nature of his vast powers.