Upkeep
Commander rules
The essentials of the format, and what Upkeep checks automatically on your decks.
01 One hundred cards, commander included
A Commander deck holds exactly one hundred cards: the commander, plus ninety-nine others. No reserve, no sideboard.
✓ Upkeep always shows your count, 93/100 for instance, and flags the gap without ever stopping you from saving — decks are rarely built in one sitting.
02 A single copy of each card
This is the singleton rule: one card, one copy. Only basic lands escape it, along with the rare cards that explicitly allow it.
✓ Upkeep spots duplicates and knows the exceptions: a card whose text allows any number of copies raises no alert.
03 Colour identity
Your deck may only hold cards whose colour identity fits within your commander's. Identity isn't just the mana cost: symbols in the rules text count too.
✓ Upkeep computes your commander's identity, shows it as mana pips next to the deck name, and flags every card that falls outside it — recommendations included, which will never suggest an off-identity card.
04 An eligible commander
A commander is a legendary creature. Some legendary vehicles and spacecraft qualify too, and a few cards read “can be your commander”. Two commanders are allowed when they have Partner.
✓ Upkeep checks eligibility when the card is added and refuses a deck with three commanders.
05 The banned list
The format bans a short list of cards. It changes a few times a year, following official announcements.
✓ Upkeep relies on the legalities served by Scryfall: the banned list is therefore always current, with nothing for us to maintain.
06 Brackets, or power stated up front
Wizards introduced a five-level scale to say, before shuffling, what kind of game you're playing. It isn't a construction rule: it's a conversation you have at the table.
Upkeep estimates brackets 2 to 4 from detectable signals: game changers from the official list, tutors, extra turns, mass land destruction, and combos spotted by Commander Spellbook.
✓ Brackets 1 and 5 come down to intent, which cards alone don't reveal — a cEDH deck and an optimised deck can hold the same cards. The estimate helps the conversation; it is never a verdict.
Going further
Upkeep summarises; the authoritative texts live elsewhere. These links open in a new tab.