The main deck has non-engine cards that are needed to cover the most meta matchups, while the side deck is used to add more coverage for these matches and to have responses to more random rogue decks that players would be likely to see in the early rounds of regional events
Hound would also potentially allow the addition of Sinister Shadow Games, which Id probably run over MST and maybe some other cards that may get hit on the next ban list (well see about that though)
By the end, youre given the aptly named Starter Deck to use in a game against the CPU
Seeking sweets and marshing mallows, Watch your back, and your candy sack
If you land on Heads, you draw 2 cards
It can banish itself to increase the level of all Mermail monsters by 1 or 2, but during its release the most important Xyz monsters were Rank 7