Companions in Magic: Rules and FAQ

Last updated on March 25, 2026

Jegantha, the Wellspring | Illustration by Chris Rahn

Companion is a very controversial mechanic. Some people love the challenges and the extra power companions can bring, while other players get tired of battling Lurrus of the Dream-Den or Yorion, Sky Nomad decks again and again. Companion cards are very interesting in Limited formats, because it’s risky and suboptimal to play companion decks, and the deckbuilding restrictions are real.

However, when we go to formats like Modern and Legacy with a much wider card pool, it’s very easy to play companion decks efficiently, so they’re the best thing to do in those formats. Today we go over all there is to know about companion rules, the power level controversy, and why WotC nerfed a whole mechanic.

That doesn’t happen every day, so stay with me and we’ll go through the whole companion debate.

How Does Companion Work?

Lutri, the Spellchaser | Illustration by Lie Setiawan

Companion is an ability found on 10 cards from Ikoria: Lair of Behemoths. The companion ability asks you to build your deck with certain restrictions. Each companion asks for something different, and if you follow the restrictions, once per game you can put the companion card in your hand. It’s similar to Commander and the commander zone, except that companion only works once per game.

The companion card starts in your sideboard, and if you build your deck following the companion’s restrictions, you may pay to put the companion straight into your hand from your sideboard. The deckbuilding restrictions are hard, but the power of the companion is worth it most of the time.

For example, Yorion, Sky Nomad can blink every nonland permanent you control when it ETBs, which is awesome, but you’ll need to play 20 more cards in your deck. Obosh, the Preypiercer doubles all sources of damage you control from permanents with odd mana values, but you can only play nonland cards with an odd mana value.

When Can You Activate a Companion Ability?

You can activate companion only at sorcery speed, which is during your main phases only. Also, you must have priority and the stack must be empty. You must pay , and after that, your companion goes straight to your hand. This is a special action that can’t be responded and doesn’t use the stack, and you can only do this once per game.

Are Companions in Your Sideboard?

Yes. When you play using the companion rule, one of your 15 sideboard cards must be your companion. If you’re playing best-of-one on MTG Arena, the companion must be one of your seven sideboard cards.

What Was the Companion Rules Change?

When companions were first released, your companion started the game in your sideboard, and you could cast it directly from there (as though it were in your hand). After companions proved to be dominant in tournament situations across various formats, WotC decided to nerf the companion rule, and now you need to pay to put the companion from your sideboard into your hand before being able to cast it.

Why Did They Change Companion’s Cost?

Although companions posed a minor power level problem in Standard, they ended up being very strong in Eternal formats like Modern, Legacy, and Vintage. Lurrus of the Dream-Den takes the cake, with this nightmare banned in Vintage, Legacy, Modern, and Pioneer. Being able to start with an extra card is very powerful, and even if you needed to build your deck with restrictions, it was worth the extra card.

Also, companions being so powerful reduces deck diversity. If everyone is playing Lurrus in a given format, cards with a mana value of 3 or greater become unplayable. Most decks were comprised of the best permanents that cost 2 mana or less.

Can You Include a Companion in Your Deck Without Meeting Its Requirement?

You can play as many creatures with the companion mechanic as you want in your maindeck without meeting any deckbuilding constraints. You’ll just play them as regular cards, without the use of the companion mechanic.

Can You Change Companions Between Games in a Match?

You can. However, you’ll probably need to change some cards between the main deck and sideboard because different companions have different deckbuilding requirements. There were some decks in Standard that swapped Lurrus of the Dream-Den and Zirda, the Dawnwaker between games because most of the cards these decks played happened to be cheap permanents with activated abilities. If all your nonland cards are different, you can change between Lutri, the Spellchaser or another companion that fits the restriction.

When Do You Reveal a Companion in Tournaments?

If you have a companion in your sideboard and you want to make use of the companion mechanic, you’ll have to reveal the companion from your sideboard before the game begins. This is needed because you can have a creature with companion in your sideboard but not use the companion mechanic altogether. Also, you can only reveal one companion at the start of each game, so you’ll have to choose the intended companion for that game.

If you fail to reveal your companion before opening hands are drawn, then you must play that game as if you have no companion.

Can You Have Multiple Companions?

You can only have one companion at a given time, provided that you meet all the deckbuilding restrictions. However, you can put multiple cards that have the companion mechanic in your deck. They’ll be treated as normal cards, and you can ignore the companion mechanic or the deckbuilding restrictions.

What Happens When a Companion Dies?

The companion is put into the graveyard when it dies, like any regular card. You can even get it back from your graveyard with Raise Dead and other gravedigger effects.

Can I Include Hybrid Mana Symbols to Meet a Companion’s Requirement?

For the purposes of Jegantha, the Wellspring, you can’t have a card with two of the same hybrid mana symbol. You can’t have a mana cost of even though the card can be paid with different colors of mana. You can have a card like Crystallization in your Jegantha deck, or Evelyn, the Covetous since the , , and mana symbols are all different.

Is Companion Banned in Commander?

No, companions are not banned in Commander. You can use companions in a Commander game.

There are two exceptions, though!

Commander's deckbuilding rules kinda soft-ban Yorion, Sky Nomad as a companion, since Yorion's requirement directly conflicts with Commander's exact 100-card deck rule. In other words, it's not technically banned as companion, but you just can't build a Commander deck that fits Yorion's requirement. Yorion is perfectly OK for the 99, though, and as an Azorius commander.

Lutri, the Spellchaser is the only one card that is specifically banned as companion in Commander, since every singleton format already adheres to Lutri's requirement, so it'd be the most stapled, auto-included card alongside Izzet commanders. It's perfectly legal in the 99 or as your Izzet commander.

How Does Companion Work in Commander?

Most companions work normally in Commander, including paying the and so on. Companions don’t go to your commander zone, and must fall within your commander's color identity.

Companions also include your commander as part of your starting deck. This means you can’t use Gyruda, Doom of Depths as your companion in a deck where your commander has an odd mana value, even if all the cards in your main deck have an even mana value.

The 100-card deck size doesn’t include your companion. Your companion is a 101st card that exists outside the game until you bring it into your hand.

Do Companions Add to Color Identity?

Companions do not add to your color identity; only your commander defines your color identity. Your companion must also be within the color identity of your commander, so an Izzet deck can’t companion Obosh, the Preypiercer.

How to Use Companions on MTGO

To use a companion like Yorion, Sky Nomad on MTGO, you must first put it in your sideboard. Here’s the information about Yorion as a companion, and the in red text shows “Companion’s deck requirements not met.”

Fill the deck with cards next. Here’s a Modern ETB deck on MTGO with Yorion, Sky Nomad as its companion. The deck must have 20 more cards than a usual Pioneer deck, so 80 instead of 60. Yorion is in the sideboard as one of the 15 possible sideboard slots.

Here’s what happens when you start a match with this deck. MTGO asks you to choose up to one companion, and in this case the only possible companion is highlighted.

Finally, the match has just started and this is the opening hand. MTGO tells you that Yorion entered the Companion Area Zone. From there, you can put it into your hand by paying .

How To Use Companions on MTGA

As you can see, the first thing you’ll do on MTGA is to add the companion to an empty deck, since it’s easier to build a deck with a companion this way. Arena uses this “yellow animal paw” symbol for companions.

Once you select Jegantha, the Wellspring, Arena asks if you want Jegantha to be your companion, and it reminds you of the deck building requirements. Click on yes. Another nice feature is that when a companion card is selected, MTG Arena turns a companion filter on, so it only lets you search for cards that meet the deckbuilding requirement for the companion. This filter can be turned off.

After that, it’s time to build your deck. This is an Explorer Rakdos sacrifice deck. No card has more than one of the same mana symbol, as you can see. Note that the sideboard has exactly one card because Jegantha isn’t in the main deck.

Now I’m playing an Explorer match with the deck. Note that at the start of the game, my companion is located on the bottom right, and it costs to put in my hand. Once I do that, I can cast it for as usual.

Here’s what happens when you try to build a Jegantha deck with a card like Elspeth Resplendent that costs . Arena lets you build the deck, but the companion mechanic doesn’t work.

Can You Have 101 Cards in Commander with Companion?

You can, actually. Your companion doesn’t count towards the 100-card limit of the Commander format. But to do that, your deck must be built with the companion rules in mind.

Can You Have a 120-card Commander Deck with Yorion, Sky Nomad as a Companion?

No, you can’t. Commander has a strict 100-card deck rule, and since Yorion, Sky Nomad requires you to have 20 more cards, you can’t use it as a companion. You can play the card as your Azorius commander () and in the 99 of a deck, but not as a companion.

Can I Use Companions and Partner Commanders?

You can. Your Commander deck can have 99 cards plus a commander, or 98 cards plus two partner commanders. If you add a companion, it doesn’t count towards the 100-card limit, and all your cards must fit the companion deckbuilding criteria, including the commanders.

Do Companions Go Back to the Command Zone?

They don’t. A companion starts the game in the command zone, and once it goes into your hand, it’s a normal MTG card. If it dies, it goes into your graveyard, as usual. In MTG’s comprehensive rules, it’s stated that “the companion remains in the game until it ends.”

Does Your Companion Need to be the Same Color as Your Commander

Yes. To play a companion in your Commander deck, it has to fit within the color identity of your commander. It’s not the same rule as partners or a commander background.

Does Companion Work in Modern?

Sure. Companion works the same way in all Magic formats they’re legal in, including Modern. Currently, you can’t play companions in the Standard format. Some companions, like Lurrus of the Dream-Den are banned, so watch out for those.

What's the Difference Between Companions and Doctor's Companions?

Companions and doctor’s companions are two totally different mechanics. Companion is a mechanic that allows you to have a companion in the command zone as an extra card, as long as you fit certain deck-building criteria. Doctor’s companion, on the other hand, is a Doctor Who mechanic that’s very similar to the “partner with” mechanic.

If you have a card that’s a doctor’s companion, like Clara Oswald, you can partner it with a time lord doctor card like The Tenth Doctor and have them both be your commanders.

Decklist: Jegantha Jund Sacrifice in Pioneer

Deadly Dispute | Illustration by Irina Nordsol

Jegantha, the Wellspring is a flexible companion, requiring only that your spells don’t have a double mana cost, and it’s a reliable way to add more power to the battlefield. This deck relies on the Cat-Oven combo, playing value cards like Bloodtithe Harvester, Fable of the Mirror-Breaker, and having flexible cards like Fatal Push and Thoughtseize coming out of the sideboard. Ygra, Eater of All speeds up the combo, getting very big quickly if you’re already saccing Food tokens.

Wrap Up

Obosh, the Preypiercer | Illustration by Daarken

Well, that’s all from me on companions. Playing Limited with companions is very interesting since a single card can alter your pick order. While they were in Standard, it was possible to see weird decks with companions succeeding. It would be interesting to have weaker companions in the future or in supplemental sets.

I don’t think WotC will mess with that design aspect soon because there’s a huge risk of making something inherently broken, or worse, uninteresting. It’s a shame that a whole mechanic had to be nerfed just to stay in the game, and we almost had a banned mechanic. And that’s something that happened only with the un-set test of stickers and attractions, and playing for ante.

What do you think of companions? Love them or hate them? Let me know in the comments below, or leave us a tweet on Draftsim's Twitter.

Stay safe guys, and in the meantime, time to play some Explorer matches with my 80-card Yorion deck while I still can.