Everybody gets in a bad situation during a Duel from time to time, when your opponent has a couple strong monsters and you just do not seem to draw what you need. "Fiber Jar" will help you survive these situations and allow you to come back and win the Duel. "Fiber Jar"'s Flip Effectshuffles everything on the field, in the Graveyards and in both players' hands back into the Deck, including itself. It is almost like starting the game over, except you still have the same Life Points. Now you have another chance to do your best and try to win the Duel.
Another good thing about "Fiber Jar" is that most people Normal Summon a monster before attacking. If you have "Fiber Jar" Setface-down, and your opponent Summons and attacks, then "Fiber Jar" will reset the field, but your opponent has already Summoned this turn and cannot Normal Summon again! This means that during your turn you can Summon a monster and attack directly!