Splinter, the Mentor

one generic mana one black mana Legendary Creature — Mutant Ninja RatPower and toughness2/2

Menace

Whenever Splinter or another nontoken creature you control leaves the battlefield, create a Mutagen token.

Partner—Character select (You can have two commanders if both have this ability.)

"We choose what holds us back."

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2.09 $

Foil 0.82 $

8 printings

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Splinter, the Mentor rulings

2026-01-27
An effect that checks whether you control your commander is satisfied if you control one or both of your two commanders.
2026-01-27
Some spells and abilities that create Mutagen tokens require targets. If each target chosen is an illegal target as that spell or ability tries to resolve, it won't resolve. The Mutagen token won't be created.
2026-01-27
Mutagen tokens are a kind of predefined token. Each one is a colorless artifact with the artifact subtype Mutagen and the ability ", , Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery."
2026-01-27
To have two commanders, both must have appropriate partner abilities as the game begins. Losing the ability during the game doesn't cause either to cease to be your commander.
2026-01-27
You can have two commanders if each one has "Partner—Character select." You can't mix and match them with cards that have other partner abilities.
2026-01-27
If your Commander deck has two commanders, you can only include cards whose own color identities are also found in your commanders' combined color identities. If Donatello, the Brains and Splinter, the Mentor are your commanders, your deck may contain cards with blue and/or black in their color identity, but not cards with red, green, or white. (If Leonardo, the Balance is one of your commanders, your deck may contain cards with any color or combination of colors in their color identity, regardless of who your other commander is.)
2026-01-27
Both commanders start in the command zone, and the remaining 98 cards of your deck are shuffled to become your library.
2026-01-27
Once the game begins, your two commanders are tracked separately. If you cast one, you won't have to pay an additional the first time you cast the other. A player loses the game after having been dealt 21 damage from any one of them, not from both of them combined.
2026-01-27
If something refers to your commander while you have two commanders, it refers to one of them of your choice. If you are instructed to perform an action on your commander (e.g. put it from the command zone into your hand due to Command Beacon), you choose one of your commanders at the time the effect happens.

Splinter, the Mentor keyword rules

Partner Rule 702.124

Partner abilities are keyword abilities that modify the rules for deck construction in the Commander variant (see rule ), 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.

Your deck must contain exactly 100 cards, including its two commanders. Both commanders begin the game in the command zone.

A rule or effect that refers to your commander’s color identity refers to the combined color identities of your two commanders. See rule .

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 ). 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 ).

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.

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].”

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.

“Partner” means “You may designate two legendary creature cards as your commander rather than one if each of them has partner.”

“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.”

“Friends forever” means “You may designate two legendary creature cards as your commander rather than one if each of them has friends forever.”

“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.”

“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.”

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.