If both players have 15 or more cards in their Graveyards: Pay 1000 LP; each player swaps the cards in their Graveyard with the cards in their Deck, then shuffles their Deck. You can only activate 1 "Exchange of the Spirit" per Duel.
In the anime it was better than this card. The version we have now, is the errata for it. It made it suck so bad now, it used to be much better and kind of op.
What they should do is replace the tip section with "Don't use this." Neither tip will help you, unless BOTH of you have a low deck count, and even then, Jar of Avarice would be ten times better for you.
It would be if it didn't have the requirement of having 15+ cards in both players graveyards. Considering that this game has 20 card decks most of the time, I don't see a situation where you would get a chance to use this card.
Except, if you're playing a deck-out deck, why would you want to refill your opponent's deck, when you could just mill another five cards for the win instead? And why waste time filling your own graveyard, when you could just focus on filling theirs?