Entering cheat mode:
Press Triangle(2), Circle, Square, Triangle, Circle, Triangle, Square at the options screen. A level number selection will appear at the bottom of the options list. Any level up to 50 may be selected in easy difficulty. Any level up to 75 may be selected in normal difficulty.

Access all spells:
Enter cheat mode and resume the game. Pause the game and press Triangle.

Increase mana:
Enter cheat mode and resume the game. Pause the game and press Square.

Complete current level:
Enter cheat mode and resume the game. Pause the game and press Circle.