Advanced mode

Advanced Mode activates when you do a level the 2nd time. It makes you complete the level three times in a row. (Three Phases) When you finish a phase you can't use items you have used in the other phases you have done before. If you quit you will have to start the phases over again.

Scribblenauts Advanced Mode Tutorial
ADVANCED MODE TUTORIAL Welcome to Advanced Mode! Advanced Mode is activated anytime you replay a level you've already completed. Once you complete this level, It will restart automatically. However, when the level restarts, you may not use any object you wrote before! Complete the level three times in a row to master the level in advanced mode. If you exit befor the three times, you will have to restart from the beginning of Advanced Mode next time.

Trivia

 * If you mastered the level and do the level again, Advanced Mode does not activate.
 * You CAN use items you have used before by typing a random letter, space button, item you want.