Lesson 10 (Judge Classes)
Although the entirety of the MTR has relevant information, below you will find sections we find to be most important for a new Level 1 judge.
A constructed sideboard must be anywhere from 0 to 15 cards. Cards do not necessarily need to be exchanged on a one for one basis while sideboarding, but the resulting deck and sideboard must still be legal after sideboarding is complete.
At the beginning of each match, the constructed deck must be returned to its original composition.
Limited decks must have a minimum of 40 cards and have no maximum size. All drafted/opened cards in a limited pool that are not in the deck are considered to be in the sideboard. A player may also request any number of basic lands to be in their sideboard.
Players participating in Limited tournaments that do not use decklists may freely change the composition of their decks between matches by exchanging cards from their deck for cards in their sideboard without being required to return their deck to its original composition before their next match. This can only be done at Regular REL.