Before drawing their opening hand, each player reveals a card from their sideboard, which may be played once from outside the game. In other words, you may play any card in your pool, including lands, as though it has companion, according to the original, pre-errata companion rules.

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How does that even work?

At the start of each game, after determining starting player but before shuffling your decks and drawing opening hands, each player simultaneously reveals a card from their sideboard. The chosen cards may be played, once, from outside the game. You do not have to pay to put it into your hand.

To reiterate, you may choose a new companion at the start of each game. Yes, this means you can "sideboard" against your opponent by switching to something that's good against their strategy, and it also means they can switch their companion to dodge your sick sideboard tech!

A few corner cases to address: Since your companion is not in your hand, you cannot cycle or otherwise discard it. You also cannot suspend a card from outside the game, only from your hand. Finally, Rebound only triggers when casting the spell from your hand, not from outside the game.

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What can I draft in this cube?

One of my biggest goals for this cube is to highlight constructed staples from various formats that have historically been too inconsistent for a drafted, singleton environment. I envision the rules change as a way to evoke iconic constructed archetypes in a way that traditional cubes cannot, and provide a novel experience in blending these archetypes together in new ways.

If you've been a fan of Modern and/or Legacy at any point in the last several years, you'll see a lot of familiar cards here, and they should be supported in the ways you're used to in those formats. If you're not familiar with constructed Magic, this section is for you. Let's dive in!

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There are many directions to take artifacts in this cube. From Hardened Scales aggro, to cheating a Portal to Phyrexia onto the battlefield, to value loops with Goblin Welder and Triarch Praetorian, if you like artifacts, you'll find your niche here.

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Similarly, there are several angles to the graveyard decks. Traditional Reanimator featuring Griselbrand and Exhume, all-in dredge with Hogaak and Stinkweed Imp, and Living End (see below) are all viable and quite strong. Pay attention to any grave hate in game one, because it could become companioned later, making a secondary gameplan critical!

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Rhinos and Living End are both powerful payoffs for companioning a spell with cascade. They can also be cast again out of your graveyard using cards like Goblin Dark-Dwellers or Dreadhorde Arcanist. Keep in mind that cards cannot be suspended from outside the game (i.e. as your companion), as exiling the card from your hand is part of the requirement to suspend it!

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Traditional aristocrats, Yawgmoth, or persist combo are all good avenues for decks that want their creatures to die. Some of the cool engines for these decks include Eldritch Evolution, Agatha's Soul Cauldron, and Cat Oven.

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Similarly, there are several flavors of decks that care about creatures entering the battlefield in various ways. As I mentioned above, Rebound only triggers when you cast the spell from your hand, so, if you companion Ephemerate, it will only function as Cloudshift. That said, you may still want to do that if you've got Grief, Solitude, and/or Fury in your deck!

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Companion an Amulet of Vigor and draft every land as though it comes in untapped! Combine Azusa, Lost but Seeking, Ramunap Excavator, and Ghost Quarter to (eventually) build your own Strip Mine! Loop Takenuma, Abandoned Mire and Wrenn and Six! Cast Golos and search for Field of the Dead! The lands synergies go pretty deep here, as well.

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Attack with legends, attack with artifacts, attack with both. You know the drill.

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Traditional control is also viable here. Companion countermagic or removal to make sure you survive to the endgame, or companion a win condition to guarantee inevitability. Either way, have a plan for the strong synergies I've outlined above.

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Because of the nature of the companion rule, I'm able to include lots of narrow one-of buildarounds that don't need a big density of support to function. As a result, there is a huge amount of room for experimentation if you want to companion your favorite constructed card of old! Some of my personal favorites are Counterbalance, Academy Manufactor, and Up the Beanstalk, but I encourage, above all else, wanton blending of synergies and archetypes into decks that marry their parts into a much greater sum.

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Why on earth did you build a cube around the biggest design mistake in Magic history?

In February 2023, I attended MagicCon Philadelphia, where I met a lot a new friends and drafted a lot of cool cubes. Among those cubes were Zach Barash's Cascade Cube and Ryan Saxe's Buildaround Cube, both of which I had an incredible time with. I loved the puzzly nature of the draft, deckbuilding, and gameplay of both cubes, and I also particularly enjoyed two aspects of Cascade Cube: first, the ability to find a particular suspend card in the draft and guarantee yourself access to it via your one drops, and, second, the exciting moment of your opponent flipping through their deck and revealing what card they had built their deck around. I wanted to capture these aspects of Cascade Cube as well as the Rube-Goldberg deckbuilding of Buildaround Cube.

I went home determined to find a simple, elegant rules change that could turn the draft on its head, like the Maelstrom Nexus emblem in Cascade Cube. I thought back to Episode 22 of Lucky Paper Radio, which is about EDH cube design. Andy had mused about the idea of removing the color identity rule, or even allowing any creature, or any card, to be your commander. At this point, the pieces starting coming together. I could allow any card at all to be your commander, but in order to avoid repetitive play patterns, I would probably want to do away with the ability to recast your commander, so it would end up functioning more like the companion mechanic. Of course, once the phrase "Companion Cube" was uttered aloud, the Portal reference was too good to pass up, and I knew the idea had to be brought to fruition.

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Please reach out on Discord (@dinrovahorror) if you ever want to chat about this project or about cube design in general!