Trash Tornado was released in Beta 12.0, alongside Librarian. Previous Versions can be found here.

Trash Tornado makes both players return all the cards they have in their hand to their deck. Then they will draw the same number of cards, so neither hand is actually changed in amount.

This can be good to swap out some cards you want to use later in game, as a sort of Mulligan. You can also use it if you think the enemy has a combo ready in their hand. Using this will very likely prevent that.