I was watching episode one of the animation TV show called Avatar. The following is the background of the sentence I am asking help for. I hope it's not too lengthy and frustrating.
The main character, a little boy who turns out to be the Avatar with superb magic power, is trapped in a big ice block. A girl frees the boy by hitting the block with a staff and the block breaks. A huge light beam goes up into the sky right after that. The prince of the Fire Nation has been searching for the Avatar in ages and he thinks this time he is going to catch him and gets carried away. He says to an old man "the ligth came from an incredibly powerful source. It has to be him!" But the old man relys "It's just a slice of your lights. We've been down this road before, Principle Zuko. I don't want you to get too exited over nothing".
What does a slice of your lights here mean? Thanks a lot for your help in advance.