Arena Cube Sealed Guide: An In-depth Look into General Sealed Strategy and Theory

Arena Cube Sealed finally arrived last week, and most avid Arena players have been keen to dive in and try it out! While there are complaints that it’s not draft and it’s true that Cube lends itself better to that, this is a great step on the road to that. My experience of the the format is that while it can be really snowbally (once your opponent starts winning, it’s very hard to stop them), it is overall a pretty fun and engaging format, especially while fresh. In this article, I’ll be giving an overview of the step-by-step process of building a Sealed deck, and then going into some specific aspects of the format while providing general analysis of Sealed fundamentals throughout. Because the format is new, this guide incorporates a lot of theory and I don’t expect it to be exhaustive; rather it should provide a useful framework for you to build on yourself!

The format is very high power compared to your average Sealed format, but unlike Legacy and Vintage Cubes which tend to play out more like Constructed, the Arena Cube still plays out very much like Limited; if you’ve had the joy of playing Peasant Cube before (commons and uncommons only, but spread throughout Magic), Arena Cube feels like a very powered-down more snowbally Sealed version of that. The main implication is that Arena Cube is much less synergy-driven than regular cubes; archetypes barely exist, and good stuff decks are the main way to go.

What is Arena Cube?

Arena Cube Sealed Card List

Want to play some limited that really packs a punch? The Cube Sealed experience grants you 6 packs like a typical Sealed event, only the card pool isn’t bound to a single Magic set! Instead, they are drawn from the creme de la creme of all the cards available in MTG Arena. Cube has no concept of rarity, so you’ll have plenty of exciting rares and mythic in your pool. The diversity of cards and the strategies and synergies make each run an exciting new experience every time! See a list of all the cards in the cube by clicking here.

Event Details

• Duration: April 4 2020 at 8:00 AM PT – April 16 at 8:00 AM PT
• Format: Arena Cube Sealed
• Entry Fee: 600 Gems or 3000 Gold
• Ends After: 5 wins or 3 losses (whichever comes first)
• Match Structure: Single matches (BO1)

Event Rewards

• 0 Wins: 3 Individual Card Rewards (ICRs) – 1 rare and 2 uncommons not in Standard
• 1 Win: 500 Gold + 3 Individual Card Rewards (ICRs) – 1 rare and 2 uncommons not in Standard
• 2 Wins: 750 Gold + 3 Individual Card Rewards (ICRs) – 1 rare and 2 uncommons not in Standard
• 3 Wins: 1500 Gold + 3 Individual Card Rewards (ICRs) – 1 rare and 2 uncommons not in Standard
• 4 Wins: 3000 Gold + 3 Individual Card Rewards (ICRs) – 1 rare and 2 uncommons not in Standard
• 5 Wins: 600 Gems + 3 Individual Card Rewards (ICRs) – 2 rares and 1 uncommon not in Standard

Cubes are essentially self-contained draft formats people build for themselves – you choose a variety of cards based on a certain theme. The most common kind of cube is a selection of really powerful cards from across formats. Modern cubes, for example, are usually a selection of the best cards in Modern, eschewing some cards that whoever made the cube doesn’t think perform well in the environment. Cube has long been an incredibly popular format and is a great way to experience Magic in a convenient and immediate way if you have a few friends lying around; they don’t even need their own cards! For some popular cubes, visit CubeTutor.

Arena Cube is, at least in theory, comprised of the best cards on Arena. In this case, some obvious cards removed are Oko, Thief of Crowns, Nexus of Fate, and Veil of Summer – the first two for power level (though Nexus wouldn’t have nearly as much support anyway) and Veil because it’s situational and not nearly as good in Limited. Historic and Arena Card pools are synonymous, but Arena Cube doesn’t adhere to the Historic banlist since Once Upon a Time is included.

Limited Rating Legend

I include my tier list Legend because I’m going to be referring to it in this article. The Legend uses Eldraine examples, but see my Theros Beyond Death Tier List and Reviews for more.

• S: Ridiculous bomb; has a huge effect on the game immediately, and threatens to dominate it if unanswered.
  LSV equivalent: 5.0 and 4.5. (Oko, Thief of Crowns, Garruk, Cursed Huntsman, Lochmere Serpent)
• A: Very powerful card, approaches bomb status, pulls you strongly into its colour.
  LSV equivalent: 4.0. (Giant Killer, Epic Downfall, Stolen by the Fae)
• B: Great playable, happy to first pick, pulls you into its colour.
  LSV equivalent: 3.5. (Bake Into Pie, Fierce Witchstalker, Mysterious Pathlighter)
• C+: Good playable that almost never gets cut.
  LSV equivalent: 3.0. (Scorching Dragonfire, Tome Raider, Wintermoor Commander)
• C: Fine playable or decent filler, sometimes gets cut.
  LSV equivalent: 2.5 and 2.0. (Outflank, Maraleaf Rider, Foreboding Fruit)
• D: Medium to bad filler, gets cut a lot.
  LSV equivalent: 1.5 and 1.0. (Tall as a Beanstalk, All That Glitters, Claim the Firstborn)
• F: Mostly to totally unplayable cards.
  LSV equivalent: 0.5 and 0.0. (Happily Ever After, Fires of Invention, The Magic Mirror)

General Sealed Strategy

Here are the steps I would recommend you take in analysing which are your best colours/which deck you should be in.

Check your Rares/Mythics

This step is irrelevant to Cube Sealed because you’ll have loads, and they aren’t necessarily better than your commons & uncommons. I also don’t think it’s that useful for regular Sealed: your rares and mythics won’t necessarily be good ones, so I prefer just using my step (a) instead, and incorporating rares/mythics as part of that.

a) Sort by best cards in each colour

First, separate all your best cards from the rest of the pool. On Arena, I like to just add them to my deck so I can look at them. After you’ve taken those in, add the good to really good cards – the cards you’re very happy to play.

Card evaluation is really important here and it won’t be the last time in this process. If you’re unsure how good certain cards are, I’d recommend looking at useful sources such as tier lists of old sets from people you trust (my Theros one is linked in the section above!) and LSV’s Limited Card Reviews, though those are made at the start of formats and rarely updated. Do take grades with a grain of salt, since they are intended for those specific formats, not Cube, and so adhere to aspects of those formats: e.g. auras and 6 drops are much better than normal in Theros: Beyond Death, so you need to lower their grade a bit. Meanwhile, a card like Ajani’s Pridemate might be far better supported in Cube and therefore deserve a better grade. One nice aspect of Sealed is that your lifegain sources for Pridemate are right there in front of you; how good it is in the format is not as important as how good it is in your pool. Because Cube is higher power, all cards but the absolute best take a slight decrease in grade, better synergy notwithstanding, because the competition against them is fiercer.

Don’t use BREAD!

I know that many of you have been taught to use BREAD as a hierarchical means of Limited card analysis. I want to encourage you to break away from that because I don’t think the hierarchies are applicable to modern magic at all. BREAD is an obsolete over-generalisation; it’s far too simplistic and discourages good card evaluation. The hierarchical aspect is actively a hindrance because it teaches you faulty methods; you should not think in terms of valuing bombs over removal, removal over evasive creatures, evasive creatures over regular creatures, etc because draft is far too contextual and nuanced, and that sort of hierarchy fails all the time. Removal being better than creatures and worse than bombs isn’t generally true anymore – a lot of creatures tend to adopt other roles, or be good at other things, and it’s very easy for a creature that has a powerful effect but isn’t quite a bomb to be better than a removal spell these days. Removal in general has gotten worse, after all, so really it happens all the time. BREAD was a more useful heuristic when most cards in packs were bad – if all but four or five cards in a pack are unplayable, it becomes a lot more valuable but that’s really not how draft is these days (thankfully).

I have an article on Heuristics which talks about the importance of building good habits from the start, so I suggest new players don’t put too much stock in BREAD either. BREAD is only really useful for teaching people what the basic terms mean so they can understand Limited discussion; one should ignore the hierarchies entirely.

b) Decide which colours look best

What colours look best is a quality vs quantity assessment – remember that you only need 22-23 cards and your goal is to reach that number with the maximum overall deck quality. Lands are still worth something – this is a format where if you’re a slow deck or one that’s playing several colours and end up with 22 playables, that’s actually probably better than playing the 23rd.

Sealed is about tradeoffs – the questions that crop up a lot are those along the lines of “should I play Black because I have The Eldest Reborn and Massacre Girl or White because I have Elspeth Conquers Death and Pacifism”?

It’s difficult to quantify this, but Limited rating scales up. What I’m about to say next is conjecture to some degree, because giving accurate numbers is impossible; again draft is too contextual, but this should still provide a useful baseline if you’re not sure how much a card of a certain power level is worth as compared to other cards.

• A mid-tier S is worth approximately two mid-tier As.
• A mid-tier A is worth approximately two mid-tier Bs.

Okay now that we’ve done those two, B vs C+ and beyond are much murkier, and really just dependent on playable counts – a B is roughly worth two C+s, but at this stage you really need to consider what you’re giving up. If your 23rd card is just a C+ anyway (so your deck is great), then the decision is obviously very simple. Generally, it’s also much better to have a B and a C than two C+s – let’s say a C+ is worth x; if that’s the case then a B is worth 2x and a C is worth 0.5x- if you go through the maths, B + a C will be worth 2.5x vs two C+s will merely be worth 2x. If you use this formula for your calculations, that might give you an estimate of what you’re sacrificing to play a colour; again I’m just generalising, so this isn’t word of law!

The ranges between the tiers can be quite large; obviously a low S might be only worth 1.5 mid tier As, or 1.2 high As. I separate the grades C and C+, so high C and C+ do not mean the same thing as I refer to them here – a mid-tier C+ is worth x as I am using it, while a high C might only be worth 0.7x or so and is worse than a low-tier C+.

c) Look at your mana base and build decks

I think a lot of people don’t put as much time into this step as they should. I recommend you build several decks; it sometimes won’t be obvious how decks compare to each other, and that’s the best way to visualise the decision. This is the stage where you’re looking at your fixing and considering splashes, or if you can even play three colours.

I did one of my earliest articles on Limited mana bases and splashing which might help some of you. Bear in mind that Arena Cube is much more punishing to colour screw (though still much less than Constructed), so you need to have a better mana base to splash – an 8/7/3 mana base with one fixer really won’t cut it here; you want two or three.

Can I splash? The two cardinal rules:

• Is my fixing good enough? The better your fixing, the more you can splash – if you can splash two colours relatively freely, then go nuts. If you have as many as 5 or 6 sources of Black, you can even splash earlier game cards i.e. I would not splash Lightning Strike often on three sources but I would on five. If your mana base is better, then the risk is lesser so you can afford to do greedier things (but remember that playing too many taplands has its own costs, especially for more tempo-oriented decks…).
• Is the card actually worth splashing? Remember that cards you splash likely won’t be played on curve, so they need to be good in the late game and they need to be good enough to incur some risk to your mana base. BREAD logic doesn’t work (explained earlier in this article) – removal is not worth splashing just because it is removal; it has to be removal that fits those two parameters. Relatedly, is the card you’re splashing significantly better than the card you would be putting in instead?

If the answer to these questions is yes, then can splash but also remember considerations like being an aggro deck, where splashing is far worse, or whether you have lots of double or triple colour cards. Just because you can doesn’t mean you should!

d) Improve your builds and prepare for the games

Whichever deck is standing out to you as the best is the one you should spend the most time on, but you should really be looking to improve all the builds you’ve made if you have time. For inspiration, I have a Limited Spotlight article here where I go through and consider possible improvements for a bunch of my decks in other formats.

Go through your reserve cards. Look for synergies, see if there’s any swaps you can make, consider your curve. The best card in your pool might be better than the worst card in your deck; you might notice 7 or 8 sources of lifegain and then a card like Ajani’s Pridemate becomes more promising etc etc.

Arena gives you infinite time so think it over a bit. Consider how this deck will play out. Are certain cards good in general but lacklustre for that plan? Is it worth switching those out for cards that are good for that plan? Don’t take huge power hits to do this, but if you’re an aggro deck then that 6 or 7 drop is a lot worse, could you remove it and instead have one less land so you can put in another reasonable playable? This is where format concerns come into play too Ask yourself lots of questions; I know for some people that this is a lot less natural than for others, but self-reflection is the key to self-improvement!

In Sealed outside of Arena, this is where you consider how you’re going to sideboard in certain matchups but you can also consider possible switches here. Doing all that before time will make everything you do in-game much faster and less stressful – if there are cards you’re not really happy to be playing, identify them either in your mind or on a piece of paper and vary it up if they’re not playing well/you do need to sideboard.

Aspects of the Arena Cube Sealed Format

Bombs vs Answers

Cube has a much higher density of bombs than a regular Limited format; many of its cards fulfil the Bomb criteria of singlehandedly warping/being able to take over a game if unimpeded. That means you’ll play against more, but playing against them isn’t as big a deal – your cards will be better able to handle them.

That’s the theory at least, but in the format as it currently is, the bombs far outweigh the removal – the unconditional removal available in Historic can often cost 3 or 4 and if your opponent is playing bomb after bomb and you play removal spell after removal spell, you are losing that exchange since their bombs probably do something before they die. Efficient removal and counterspells are how decks in regular Cubes handle bombs – if your opponent plays a 5 drop bomb and you remove it and play a good 3 drop, you’re pretty far ahead in that exchange, but unfortunately the Historic card pool doesn’t have access to enough efficient answers to keep up. Conditional answers will also commonly fail you – what if your opponent plays Bolas’s Citadel, Divine Visitation, Ethereal Absolution against your hand full of creature and planeswalker removal? Kiora Bests the Sea God is perhaps the most frightening example of this… better have a counterspell!

What all this means is that the format is very much a prince format – your bombs will be winning the games, you’ll just have more of them. Don’t rely too much on your expensive removal to win you games; it’s not as good here as in a regular Limited format!

Sweepers are absolutely crucial for the slower decks in this format – they break the cycle of bomb removal bomb removal, since you can allow some of the bombs to stick around if they don’t have as immediate an effect (something like Archon of Sun’s Grace, you can definitely ignore for a while). There aren’t enough that people will play around them as much as in Constructed, but they will more than in regular Limited. Still, you might be able to capitalise on their hesitation, giving you a chance to catch up, something that’s going to be really hard to do otherwise. Cheap sweepers are much better than expensive; one of the best t6/7 plays that can actually stabilise you is getting to go 4 drop sweeper into 2/3 drop.

Packages, not Archetypes

In general, the format’s synergies are more like packages than archetypes – you can dip into the packages to enhance the individual power of your cards but the card power level is divergent enough that just playing the best cards you have will win you the most games. That’s why I haven’t provided an archetype guide; Limited Card Analysis is way more important here. The only archetypes that I think actually exist are multicolour good stuff, often 2 or 3 main colours splashing 1-3 more (which kind of goes against the idea of an archetype in the first place in how divergent it is…), Ramp (which often incorporates multicolour good stuff), and red and/or white aggro. Do those seem really general to you? That’s because they are!

With packages, the important thing is to consider how the cards play generally. The better a card is by itself, the less synergy you need to include it in your deck. Let’s look at Ajani’s Pridemate – that card is mostly a 2 mana 2/2 if you don’t have much lifegain; maybe it’ll become a 3/3 on t4. If that doesn’t sound that exciting to you in a format full of the best cards in Historic, you’re thinking along the right lines. In order to play Ajani’s Pridemate, I’d want about six early (because Pridemate isn’t good late) Lifegain sources in my deck, but they also need to be good by themselves i.e. I’m not going to play Soul Warden, a terrible card by itself, just for this purpose because I might just draw the Warden and not the Pridemate. If Soul Warden is good in my deck i.e. I have maybe five or six other good reasons to gain life, then sure that counts.

I got to six using a hypergeometric calculator; see the image on the right. I have a strategy article on what all this means and how to use these, but essentially the number at the bottom there is the % probability of drawing Pridemate alongside a card that fulfils the parameters. It doesn’t take into account the probability of actually connecting and getting the counter, so it’s actually a good deal lower than this indicates – your opponent might just kill your lifelink creature, after all. That’s offset by the fact that Pridemate is a 2 mana 2/2, so it’s not the worst thing to just have around and you can sometimes just trade it off for their 2 drop. Click here if you’d like to know how I got these numbers (a quick explanation at the end of this article).

I don’t consider Ajani’s Pridemate particularly great in this format, because see this Scryfall list of cards that gain life (you can see my search query at the top in case you want to do this yourself; there’s a Syntax button on the right of it which will teach you) – there are only 31 cards in White that gain life, and this includes stuff like Adanto Vanguard and Afterlife cards which don’t work. Additionally, some of them just aren’t that relevant – if your Dream Trawler is attacking or your Lyra Dawnbringer has lived long enough to attack, is the counter on Pridemate really that big a deal? Are you planning for these two best case scenarios?

That being said, we’re playing Sealed! Your pool might just happen to have Daxos, Leonin Vanguard, Alseid, Charming Prince, Birth of Meletis, and some Lifelink creatures in it, and you might have Heliod and other such payoffs for doing so. Together this forms a package of synergistic elements.

Meanwhile, if the card you’re considering is Heliod, that card does a lot more by itself, including enabling itself and becoming a threat if you have enough white devotion. It’s way more likely that Heliod will be something you’re happy to draw anyway so you might only need 2 or 3 other lifegain sources to justify his inclusion (if any at all – depends on your deck). That being said, you still shouldn’t count stuff like Dream Trawler or Lyra Dawnbringer as synergy, because the counter still isn’t that relevant when they’re successfully connecting; it’s half a teaspoon of sugar on top of your giant victory parfait.

I hope having an idea of the numbers, and how to calculate this stuff yourself, gives you the best tools for analysis of whether you should adopt one. There’s also the question of what cards you’re sacrificing in doing so – including a package often involves some power level sacrifices and those can mount up if you end up cutting more and more cards. Ask yourself whether it’s actually worth it at the end, or if you could drop some of the package for the sake of power and still have the remaining parts function.

The Smaller Stuff

• Planeswalkers appear far more often than in regular Limited; those of you who have drafted a lot of War of the Spark will have an edge! In general, this means that getting onto the board with creatures is more important – you don’t want to take turns off doing other stuff early, because the average deck even in Arena Cube won’t have tons of ways to remove them, and you could find yourself falling really far behind. You also don’t really want to be holding cards too much – if you can use your mana, it is more important to do so. Your decks should have more removal than in Limited and there will be better early targets for it, so saving removal won’t be as feasible.
• In expensive durdly midrange decks with lots of bombs, I would recommend playing 18-19 mana sources over 17 mostly (so lands, mana rocks, Grow from the Ashes etc) – you’ll have more to do with your mana and really want to be able to double spell quickly; if when your 5 and 6 drops resolve, they’re just crushing and generate a ton of value (especially if they draw cards) then that’s a great reason to have more lands.
• Being on the play is a a greater advantage than in regular Limited – planeswalkers are much better on the play, and higher power level formats in general increase this effect anyway, but the most important reason is what I said about bombs vs removal earlier – if you start to win in this format, it’s very hard to stop you apart from using Sweepers (and Sweepers are better on the play too since you’re more likely to be able to stabilise with sweeper + creature, and they’re more likely to come at a relevant time before the bombs have overwhelmed you).
• Aggro is still harder to make work in Sealed because your curve just won’t line up, but when you can actually have a good curve alongside good removal/tricks/reach, you should absolutely go for it. People won’t be prepared for good aggro decks, so you can often just run them over – it’s worth taking a small sacrifice in deck power to play a good aggressive game.

Final Thoughts

Sealed tends to be more bomby to begin with, but I do think the format’s problems hurt its longevity. I look forward to draft’s inclusion, since I do think the overly good stuffy and snowbally aspects are solved to some degree there. That being said, I love having new formats to adapt to and develop my understanding of, and I recommend every fellow Limited Lover dips their toes in and tries it out, especially since it’s not here for all that much longer. I don’t think this format really ascends to the lofty heights of Cube, which is usually considered one of the best Draft formats, but it is certainly a unique experience we haven’t seen on Arena before.

Thanks for reading!

Compulsion’s and my first Ikoria Limited Set Review (White) releases either later today or on the 12th. After that, each day there’ll be another Review each day, after which we’ll follow up with a full Tier List, so stay tuned!

• As always, you can find all my articles, the whole shebang from all things Limited to Strategy Articles to Deck Guides at mtgazone.com/drifter. If you don’t see anything specific then I’d recommend my Limited Spotlight Series.
• I offer Limited coaching at negotiable rates. Learn some fundamental skills in a few short hours! Contact me through the discord/reddit for info.
• If you’re looking for a good draft streamer to watch, I recommend www.twitch.tv/justlolaman. Lola is a a strong Limited player and good teacher, and a long-time friend of mine!
• Feel free to follow me on Reddit here to be notified as many of my articles come out, or sign up for our site newsletter at the bottom of the home page for all of them!
• The MTG Arena Zone discord: https://discord.gg/SPYMExR. Engage with your favourite MTGAZone content creators there, myself included!

Calculation

For people interested in the specific calculation in the Packages section:

• It’s 39 because we remove the Pridemate from our pool since we have to have drawn it.
• 6 for 6 lifegain sources.
• 8 because here I’m looking at t3 on the play (it’s better to average both play and draw for around 79.6% – but you’re also less likely to actually get the counter on the draw) so 7+2 draws on the play minus one because Pridemate must have been one of our draws.
• Number of successes in sample is 1 because I’m just looking for the third counter in this hypothetical (though really that’s not enough to make Pridemate a great card).