A Sorare: MLB roster consists of seven cards. You'll need to fill the following positions:
1 Starting Pitcher
1 Relief Pitcher
1 Corner Infielder (which can be a 1B, 3B or DH)
1 Middle Infielder (which can be a 2B, SS or C)
1 Extra Hitter (this can be any hitter)
1 Flex (this can be any player)
You can only use each card once per Game Week, and you can only use each player once in the same lineup - even if you have two of their cards. You'll also need to make sure your lineup has at least two MLB teams represented in order to be valid.