How do you know if a deck is good?

There are many decks that you can use to achieve your goals in Magic Arena. Wherever you had copied one online or are making one yourself, there are a few important features you need to be mindful of.

A deck is 60 cards in constructed, 40 cards in limited

You may include up to 250 cards in Magic Arena in constructed and 60 in limited. But you shouldn't do that.

The main reason for this is that every card you select for your deck should be good. And ideally you would want to see this card in your hand as often as possible. This means that you have to keep the deck size minimal to maximize the chance to play these specific cards.

Please note, that there are good commons and bad mythic rares, so rarity is not a direct measure of how good a card is. Making sure that your main gameplan uses the maximum copies of the cards (4 in constructed and as many as you can in limited) while maintaining the minimum possible allowed decksize goes a long way to increasing the deck consistency.

If you will be playing best of 3 matches (traditional constructed & limited) you should also note the sideboard. Those are additional cards you can use to shape your deck after the first match. This means you have to be mindful of the cards in the sideboard. However, it's a more advanced topic to be covered later.

Cutting cards in your deck to this minimum is an iterative process and highly important in any MTG deckbuilding execise.

Having a plan

You don't have to be the best deckbuilder to be the best MTG player in the world. There are many top players that are not that good at constructing decks and have others do that for them. But you must know how the deck that is built functions. It must have a plan and a back up plan, and all the cards must advance this plan or help it take shape

The plan of a deck is closely linked to the archetype of the deck and will be discussed in greater deal in the next section of this guide. For now it would suffice to say that if the deck you're using has an unfocused plan, e.g. using a 6 mana spell in an aggresive deck that's good only in the early game, you're likely not bringing out the full potential from the deck.

The Manacurve

You want to have an optimal amount of lands in your deck, as they enable you to play your creatures and spells.

You want to avoid three types of situations. You don't want to have too little mana. This would prevent you from playing spells. If you have only 3 mana and 7 cards in hand that cost 4 mana and more this is called mana screw. You want to avoid having too much mana. If you have 7 lands and three cards that cost 1 mana on the battlefield, that's called mana flooding. You don't want to have lands of one type of mana while the cards you need to cast are of different mana requirements. If you have mountains only and 4 white cards that you can't play, that's called color screw.

To avoid those three types of situations as much as possible there are some general rules of thumb regarding how many lands you want in the deck you're playing and how you play those decks. This doesn't mean that there are no exceptions, but this is a true and tested guideline.

Aggro

Aggresive decks that want to win in the early game (3-6th turn) are called aggresive decks or aggro. Those decks want to deal as much damage as possible as early as possible. To achieve that they play creatures and spells that cost little and can help this plan as much as possible.

Examples of those deck in Magic Arena include the ever popular RDW (Red Deck Wins), Weenie White, Boros Tokens, Rakdos and Red burn and many other versions. Go fast at the start and you don't have to worry about your opponent's late game threats!

Those decks usually want to keep their curve low and can get away with having 18 to 20 lands depending on their color requirements and the actual curve. Including creatures and spells that cost more than 3 mana in those decks, i.e. rekindling phoenix and experimental frenzy should be done carefully and keeping in mind the curve, adjusting it to accomodate.

The downsides of most aggresive decks are mass removal spells and moderate amounts of lifegain. If the game stalls into mid and late game the aggro loses a lot of momentum.

By going above 20 lands you're approaching the aggro-midrange territory. We'll be monitoring the development of decks that can potentially be called such. Examples may include token decks such as Selesnya tokens and Mardu Humans.

Midrange

Decks that are not aggresive and don't fall into the control category are usually called midrange. Most Combo decks are also midrange and we'll briefly cover them as well.

A midrange deck wants to be the strongest in the midgame. Against aggro strategies it might employ mass or targeted removal and build the board aggro strategies can't easily breach. Using the card advantage engines allows midrange to outvalue aggro. Against control midrange decks want to race them, dealing damage and applying pressure as soon as possible. If this is not possible, midrange decks should usually have some sort of disruption plan, for example targeted discard (duress) and resilient threats (e.g. carnage tyrant).

Such decks want to have access to powerful mid-game spells. To do that they need to be able to reliably play 4-6 mana spells reliably and need 22-24 lands in Magic Arena. Midrange decks are usually in more than one color and as such need rare dual lands that can come into play untapped. This is one of the reasons why midrange lists can cost a lot of rare wildcards in Arena.

Combo

Combo decks mostly fall into the midrange category. Combo deck assemble the pieces to win the game in one or two turns. The rest of the deck is dedicated to drawing those pieces and protecting them. An example of a combo deck in Magic Arena is a famished paladin combo

Famished paladin untaps when you gain life. If he has lifelink, e.g. from squire's devotion and a way to deal damage to the opponent via sorcerer's wand. You gain life from this damage and untap the paladin and repeat as needed 20 or 120 times.

The rest of the deck may be build around protecting your combo pieces, for example having the paladin gain hexproof and draw spells to enable the combo. Of course, combo decks may be more difficult to assemble. Magic Arena combo decks include Polyraptor, mill and turbo-fog among others.

Tempo

We have touched upon aggro-midrange earlier. If a deck plays like midrange with elements of control, it's called tempo. This type of deck wants to win with creatures and foil the opponent with bounce and counterspells. In Magic Arena the most typical tempo deck is Mono U

This monoblue deck relies on creatures with flying and unblockable to deal damage, curious obsession to draw additional cards, counterspells to prevent removal and mass removal. Due to having only one color Mono U tempo in Arena plays fewer lands than most tempo lists, content with 20-22 lands.

Control

Control decks want to control the pace of the game to the maximum possible extent. Usually this entails removal, mass removal and counterspells.

A control deck shines in the late game. In the late game a control deck usually has huge threats that can finish the game in a few turns, e.g. Chromium the mutable or Niv-Mizzet. The current control lists also feature cards like Teferi that comes online much earlier and can take longer to win due to how long it takes to mill the opponent.

Control decks need to have a wide array of answers to decks they face. Doing so is surprisingly difficult and requires a good manabase with lands that come into play untapped. Control want anywhere between 24-26 lands and most of them must have the option of coming into play untapped. The difference between a turn 4 and turn 5 mass removal can mean the difference between winning and losing a game for a control player.

As such, control lists in Magic Arena are usualy three colors (Dimir control is strictly speaking more midrange) and that requires very expensive mana base in terms of the rare dual lands

Conclusion

Wherever you're using a deck somebody has made or making your own you should now be able to tell what kind of archetype it belongs to and how to tell if it's in a good shape or not. If you're getting into trouble with mana, don't forget to check the chapter on the RNG that deals with some Magic Arena quirks and misconceptions of probability.

Meanwhile, we're moving on to how those archetypes interact with each other and which archetype is the strongest. Find out in the next chapter of the guide!