If you could have a superpower what would it be

If I could have a superpower, it would be the Power of Word. Power of Word means, that everything I say becomes true in some time. For example, I saw a boy, who does the homework. The algebraic equation is very difficult for him, and he has been working it out, but it doesnt gives any results. And I can come to him, and say: You will work it out. And after some time, I can hear hid voice, shouting Yeah!
This superpower is difficult to use, the owner of this superpower must be wise and clever, otherwise it will lead to bad consequences.