The Edge of Eternity — G.L. Breedon

As he nears his sixteenth birthday, Gabriel Salvador becomes more central than ever to the War of Time and Magic.  

When the fate of the entire continuum is threatened by the plans of malignant mages, Gabriel must figure out how to protect the girl he loves while defending the timeline of history from utter destruction.  

From the Great Wall of China in 1644, to the Battle of Lepanto in 1571, to the deep past of the Paleozoic Era and the palaces of a dark alternate world, Gabriel battles against impossible odds to decisively end the war in this final adventure of The Wizard of Time.