Partner
Partner is a keyword ability specifically used in the Commander format. Partner was introduced in Commander 2016.[3][4] The Partner with variation allows only a specified other card to be the partner, but also allows a player such as a Two-Headed Giant teammate to tutor for the other card.
From the Comprehensive Rules (November 8, 2024—Edge of Eternities)
- 702.124. Partner
- 702.124a Partner abilities are keyword abilities that modify the rules for deck construction in the Commander variant (see rule 903), and they function before the game begins. Each partner ability allows you to designate two legendary cards as your commander rather than one. Each partner ability has its own requirements for those two commanders. The partner abilities are: partner, partner with [name], friends forever, choose a Background, and Doctor’s companion.
- 702.124b Your deck must contain exactly 100 cards, including its two commanders. Both commanders begin the game in the command zone.
- 702.124c A rule or effect that refers to your commander’s color identity refers to the combined color identities of your two commanders. See rule 903.4.
- 702.124d Except for determining the color identity of your commander, the two commanders function independently. When casting a commander with partner, ignore how many times your other commander has been cast (see rule 903.8). When determining whether a player has been dealt 21 or more combat damage by the same commander, consider damage from each of your two commanders separately (see rule 903.10a).
- 702.124e If an effect refers to your commander while you have two commanders, it refers to either one. If an effect causes you to perform an action on your commander and it could affect both, you choose which it refers to at the time the effect is applied.
- 702.124f Different partner abilities are distinct from one another and cannot be combined. For example, you cannot designate two cards as your commander if one of them has “partner” and the other has “partner with [name].”
- 702.124g If a legendary card has more than one partner ability, you may choose which one to use when designating your commander, but you can’t use both. Notably, no partner ability or combination of partner abilities can ever let a player have more than two commanders.
- 702.124h “Partner” means “You may designate two legendary creature cards as your commander rather than one if each of them has partner.”
- 702.124i “Partner with [name]” represents two abilities. It means “You may designate two legendary creature cards as your commander rather than one if each has a ‘partner with [name]’ ability with the other’s name” and “When this permanent enters, target player may search their library for a card named [name], reveal it, put it into their hand, then shuffle.”
- 702.124j “Friends forever” means “You may designate two legendary creature cards as your commander rather than one if each of them has friends forever.”
- 702.124k “Choose a Background” means “You may designate two cards as your commander rather than one if one of them is this card and the other is a legendary Background enchantment card.” You can’t designate two cards as your commander if one has a “choose a Background” ability and the other is not a legendary Background enchantment card, and legendary Background enchantment cards can’t be your commander unless you have also designated a commander with “choose a Background.”
- 702.124m “Doctor’s companion” means “You may designate two legendary creature cards as your commander rather than one if one of them is this card and the other is a legendary Time Lord Doctor creature card that has no other creature types.”
- 702.124n If an effect refers to a partner ability by name, it means only that partner ability and not any others. If an effect refers to the partner ability or cards with partner and doesn’t mention a specific variant of the partner ability by name, it is referring only to partner, partner with [name], or cards with either of those abilities, and does not refer to any other partner variant.

History
A player can have two commanders if both have partner. Because both commanders start the game in the command zone, the remaining library is only 98 cards. Your two commanders are treated individually for all other Commander rules. If either leaves the battlefield, you can return it to the command zone instead. The “commander tax“, the additional cost of 2 for every time you’ve cast a commander from the command zone, applies individually. Combat damage dealt by each commander is similarly tracked individually. If either commander can deal 21 or more combat damage to a single player over the course of the game, that player loses.
If any card refers to your commander (or commanders in general), it means either one of the two.
Partner was heavily featured in Commander Legends, where it appeared on 40 monocolored (and one colorless) legendary creatures and planeswalkers.[5]
Note that while the Partner ability does not explicitly prohibit a card from being partners with itself, the singleton rule of Commander formats prevents it nonetheless.
Partner in practice
Partner only deals on Commander games being able to mix and match Partner creatures of your choosing to benefit from either their effects or color identities to match your strategy.

