Before I tell you that you need to have exactly 40 cards in your Main Deck and 15 in your Side Deck, ask yourself if your goal is to win. Whether you’re 6 or 66, you should be playing 40 cards in your Main Deck if you want to win unless you have a good reason or you just don’t care.
Here are some of the reasons I’ve seen people justify playing more than 40 cards.
I’m superstitious and need my deck to be a prime number.
This is not a good reason.
I play cards that devour my deck.
Pot of Cupidity is the only card that would justify playing more than 40 cards by itself. Even then, I’m unsure of how great that is.
I don’t want to get decked out.
Lightsworn ends the game quickly enough that it shouldn’t matter. And if your opponent is playing a deck that wants to mill you out, they’re not going to do too well in tournaments. If you’re doing well, don’t sweat playing against random mill decks.
My deck plays a lot of searchers and I don’t want to draw certain cards.
Just play 1 Garnet, 3 Brilliant Fusion. Here’s a quote from a Magic player that played 66 cards with a bunch of searchers. Keep in mind, the minimum in Magic is 60.
“This deck needs to be cut down to 60 cards. All this rationalizing is just wrong. I am not sure what all cards to cut, but I know that I want to draw my good cards more, as well as get better mana draws. … There may come a day when it is right to run more [than 60 cards], but that day has not yet come.”
I just don’t know what to cut to make it 40.
It can be hard figuring out which card(s) is the worst card(s) in your deck. But one card is the worst.
So you have 40 cards in your deck. If you have 40 different cards, each card has a 12.5% chance of appearing in your opening five. It increases to 15% going second when you see six cards. Between 12.5% and 15% isn’t a lot. Which is why you play two or three copies of certain cards. Want to always open with Speedroid Terrortop? Play three. Drawing five cards gives you a 33.76% of opening one, two or three copies of Terrortop.
You can go lower than 40 cards with cards like Upstart Goblin or Chicken Game. Currently, Chicken Game is forbidden and Upstart Goblin is limited, but they may both be unlimited again in the future. They don’t actually lower your deck count, but effectively do. For a minimal cost, usually LP, some cards let you run less cards. You should always maximize on these cards unless your deck cannot handle the LP change.
Running 40 cards is most important in decks where you need to draw certain cards. If you’re playing a deck where you can draw pretty much any hand and still play, it’s less important, but still important. When Nekroz were released people played 44-45 card decks because every card searched another card and you didn’t want to draw Djinn, Releaser of Rituals. With 40 cards, you have a 12.5% chance of drawing the Djinn. That chance only goes down by increasing the number of cards in your deck. But it’s not like it’s useless in your hand. Maybe you’d want other cards, but that’s why there was only one copy in the deck. If you don’t have to search Unicore with Brionac, maybe you could search the Valkyrus instead because you naturally drew the Unicore. Having a more consistent deck gives you more options.
You can argue that playing more cards allows for more options, but it really doesn’t. There are only so many things you can do with any given hand. If your game plan is to Tribute Summon Erebus or Ehther on your first turn, you want to be able to do that every time. While true, running more monarchs like Thestalos gives you a higher chance of opening with something to Tribute Summon, you’re less likely overall to have the tribute fodder you need. If Erebus and Ehther both said you win if you Tribute Summon it, the ideal deck would be 1 Erebus, 1 Mithra, the Thunder Vassal and 1 Domain of the True Monarchs. You can’t run only 3 cards, or 5, or 25. The minimum is 40, so we want to maximize the cards we want to see.
This deck made it to Top 4 at the latest YCS. This deck wants to be able to Tribute Summon on turn 1, but it is willing to sacrifice some of that consistency for longevity and the ability to make other plays. The deck is still 39 cards with other consistency boosting cards like Pantheism and Tenacity. Playing the full playset of both as well as three Brilliant Fusion and four ways to summon a Quantum Layer before Tribute Summoning. Despite my dislike for Tribute Summoning, this deck does it consistently. Out of the 19 decks we know about in the top 32, not a single one was over 40 cards. And 13 out of those 19 all ran Upstart Goblin.
Let’s look at this another way. Roland Fang decided that Domain was worse than any other card in his deck. Fang also decided that the third copy of Kuraz was worse than the third copy of Erebus, which is an easy distinction to make, but you need to think about the worst card in your deck. It gets worse after game 1. In games 2 and 3, Roland Fang presumably wanted to draw his Ghost Reaper when playing against Burning Abyss, which is why it’s in the deck. Going first, Fang has a 34.52% chance of drawing Ghost Reaper in his first five. Going second we can’t discount Upstart Goblin because it can’t be used on the opponent’s first turn, so Fang has 3 out of 40 cards that are Ghost Reaper going second if he wants to use them on the first turn of the duel. That changes the odds of seeing Ghost Reaper to 39.43%. In order to do well at a tournament, or in any game, you need to maximize your chances of winning. And part of that is maximizing how consistently your deck can do what it wants.
If we pretend the Kaiju don’t exist, Quantums can still summon King Magnus on their first turn. The consistency went down with the hits to Emergency Teleport, Upstart Goblin, Chicken Game and Reasoning, thus decreasing the consistency of the deck. An article I read a long time ago stated that there is a best card for every scenario. If your opponent has an Ultimate Falcon, monsters with high ATK or the Kaiju become the best card in your deck. If your opponent has no cards, you’d like to draw cards that help you deal 9000 points of damage.
Compared to Yugioh, every deck in Magic is basically a slow combo deck. If you look at mtggoldfish.com, every list has 60 cards in it. Of course, 60 is the minimum amount of cards you can run, but you need to be able to do what your deck wants to do. The original Magic deck size was 40, but decks were too consistent, so it was increased to 60. Magic players have been playing Magic since 1993. Yugioh may be very different from Magic on a lot of fundamental levels, but both games start with an opening hand and have a deck minimum. Magic is 26 years old, and all of the pros play 60 cards unless they’re goofing off.
The only times I can think of when I played more than 40 cards were Nekroz and Lightsworn Rulers. Nekroz should have been slimmed down to 40 because I wanted to see my Brionac, which was semi-limited. And with Lightsworn Rulers I got lazy and didn’t cut the worst card in my deck, which was easily identifiable as Skill Prisoner.
Go to yugioh.party (that’s the actual url) and do the math for yourself. Running less cards in your deck total leads to more consistent hands. If you like losing, you can sleeve a 50-card main deck and play without a side deck with these sleeves. Until tomorrow, click an ad and make sure your friends are playing 40 cards. Friends don’t let friends play more than 40 cards.
Bonus: I don’t like Tribute Summoning or Ritual Summoning because you still need to tribute something. I’m not a black mage.