It provides customizable randomized setups of all variable cards in the game. If there's a card you don't like, set it to "Unlikely" and it won't show up all that often. Despise a card? Set it to "Always Off" and it will never show up. Want to always see a card in your random setups? Set it to "Always On".
There are a number of other options as well, including the ability to always have one of each type of card, and to ensure that defense cards are only present if there are attack cards available.