1 commander card (any legendary creature or planeswalker)
59 other cards
Only one copy of any card, except basic lands, or if a card directly contradicts this rule
All cards must be in the color identity of the commander
2–6 players
Free-for-all multiplayer format
With 3 or more players, start at 30 life; with only 2 players, start at 25 life
The first mulligan is to seven cards, then each mulligan afterward results in one fewer card (six, five, four etc.)
All commanders start in the command zone
Take turns in clockwise order (Unless someone in a silver-bordered game plays Topsy Turvy)
Last player standing wins
A card's color identity can come from any part of that card, including its casting cost and any mana symbols in its text. Every card in your Spellcaster deck must only use mana symbols that also appear on your commander. Colorless cards are allowed as well.
This is where your commander resides during the game when it is not in play. At the start of the game, each player puts their commander face up into the command zone. A commander can be cast from the command zone for its normal costs, plus an additional two mana for each previous time it's been cast from the command zone this game. If your commander would be put into your library, hand, graveyard or exile from anywhere, you may return it to your command zone instead.
There is no commander damage. This is only here to remind you so you don't play using commander damage.
There are no sideboards in Spellcaster.
Abilities which bring card(s) you own from outside the game into the game (such as Living Wish; Spawnsire of Ulamog; Karn, the Great Creator) do not function in Spellcaster, except for companion cards. You may have up to one card in your sideboard as long as the one card has companion. Companions do not have to be in your color identity. If you have a companion, your commander and your 60 card deck must follow it's deck building rule.
If your commander has partner, you may use two commanders as long as both commanders have partner. Your color identity is determined by both your commanders' combined color identities. Use this rule for your deck size: Deck size = 60 minus the number of commanders.