My MS is YA fantasy. It has a significant plot twist in the end. The best example I can think of that most people will understand is the Sorcerer's Stone - Harry thinks Snape is helping Voldemort, when it's actually Quirrell. My story is not at all like HP, but this is the type of plot twist.
Can anyone suggest any recent YA fantasy examples? I've studied the genre for so long, but most of the examples I can think of are from 10 years ago (e.g. Cassandra Clare's City of Bones).