For the maze you're in:
Go around to the right side of the maze, and change the barriers as you go. You'll kinda go around in circles a bit but the exit will be reached from the left, not the right.
As for the final boss, it's gonna be an hour or more in the battle, and the boss will one-hit kill everyone at once. Use "Best Ally" or "Safety" after every time someone gets killed. There's no surviving the major attacks from this boss, so if you don't have safety or best ally, it'll be game over.
The boss doesn't heal itself, so the battle relies on being able to survive long enough to reduce its HP. At the last part of the battle, there will be a countdown; you have to hit it with everything you've got before the countdown reaches zero or it's game over.
In other words, the final boss is freaking difficult. I had my characters on level 56 or 57 and it was still by the skin of my teeth.
