Historical Rules · 23 April 2010
Rule 713.2
Official source text from the 23 April 2010 Rules release
As the subgame starts, an entirely new set of game zones is created. Each player takes all the cards in his or her main-game library, moves them to his or her subgame library, and shuffles them. No other cards in a main-game zone are moved to their corresponding subgame zone, except as specified in rules 713.2a-c. Randomly determine which player goes first. The subgame proceeds like a normal game, following all other rules in section 103, "Starting the Game."