We’ve all been there. You have exactly the cards you want in your latest deck; but suddenly someone comes along with a cool tech or genius inclusion that would work perfectly. The problem is, you only have 30 card slots. How do you make the painful decision of what card to cut?

The answer is rarely easy. Telling what cards are under-performing and what cards aren’t is a subtle challenge. Following these steps can help you figure out what can’t quite make it in.

Step One – Play the Deck (A lot)

Understanding how to tweak decks is largely dependent on understanding the deck itself. A fundamental knowledge of the structure and gameplan of the deck’s strategies is necessary to know how to optimize them. If you’re going to add cards, you need to know what cards will work with the strategy. It’s a common error to jump straight into a netdeck and try and make changes after a loss or two without experience with similar archetypes.

For instance, if you’re losing a lot as Taunt Warrior to Freeze Mage, a player who’s less experienced with the deck might assume that the best tech card would be the addition of an Eater of Secrets to punch through Ice Block; but someone who’s more experienced would recognize the superior power of an Armorsmith or two to generate burn-breaking armor. Similarly, a player who was unused to the gameplan of Midrange Hunter might consider adding a N’zoth for the sweet Savannah Highmane Synergy, unaware of the intense tempo focus of the deck.

Step Two – Differentiate Between “Core” and “Flex” Cards

Most decks have cards that are “core” to their strategies, cards that are instrumental to the implementation of their gameplan. Examples of this include N’zoth’s First Mate in Pirate Warrior, Kill Command in Midrange Hunter, Shadowstep in Crystal/Quest Rogue, and Ice Block in Freeze Mage. Cards like this aren’t simply strong, they define what makes the deck worth playing in the first place.

Flex cards can be harder to pin down. They are most easily defined as “Cards that are sometimes cut.” History can be your guide here; if you look back through previous incarnations of the archetype, see if the card was included. If at any point, without being replaced by a card with a similar function that no longer exists, it was voluntarily excluded from successful competitive lists, it would likely be considered a flex card. Examples of this can include meta-dependent tech cards like Acidic Swamp Ooze or Hungry Crab, but can easily include clunky, semi-synergistic choices. Think a second Gadgetzan in Jade Druid, Arcane Giants in Miracle Rogue, or Stampeding Kodo in Midrange Paladin. These are the cards that should be on your proverbial chopping block. (Note that the second copy of a card can be a flex spot while the first remains core; many Control Warriors would cut a single Brawl or Acolyte of Pain at certain points in the meta, but none would cut both copies).

Step Three – Watch your Matchups

Cards are rarely objectively superior to one another. Many cards could conceivably find a place in very many lists. The complications arise in when they are superior. A classic example is whether to play low cost or high cost cards. Low cost cards are usually superior in fast-paced board-centric matchups, as they can be played in vital early turns. Meanwhile, higher-cost cards allow you more late-game pressure and value to beat out heavier lists in long games. Through these sorts of trade-offs, you can precision-engineer the type of matchups you want to gain an edge in.

But what matchups should you focus, and how? Making the decision of what matchups to sacrifice and what to improve on can be tricky. As a rule of thumb, it’s generally best to try and improve your most common near-evenly favoured opponent. Since the games tend to be close, small edges can make a difference. When as a Taunt Warrior, it will take a lot to even occasionally win your matches against Jade Druid; however, a few key changes like a second Sleep with the Fishes can massively improve your winrate against a close matchup like Murloc Paladin.

Step Four – Notice the Boring

Sometimes our human perceptions and biases can hinder us. Take the instance of Kindly Grandmother and Deadly Shot in Midrange Hunter. Kindly Grandmother is rarely spectacular. It’s a slightly above-average two drop that enables certain beast synergies. Your opponent will not be defeated by Kindly Grandmother alone.

Meanwhile, Deadly Shot is almost always interesting and makes an impact. At three mana, it can snipe that vital minion or clear a taunt for lethal. Often you will pray to topdeck it, and it will obviously win you games. However, despite all this, Kindly Grandmother is almost always a better inclusion. Kindly Grandmother provides low key, reliable, non-situational tempo and a strong beast synergy activator. This is incredibly paramount in a deck reliant on curving out game after game. While Deadly Shot is far more flashy, the times when it sits in your hand or just hits a 1/1 can be hard to remember.

As such, it’s vital to try and think about your cards and review your games to determine when cards were “boring” but good, and “boring” and bad. Remembering only the flashy, unlikely, or impactful games will lead you to warped conclusions.

Step Five – Experiment

So you’ve got to know the deck, identified your flex slots, targeted a matchup or two you want to improve, and figured out that card that seems clunky or redundant to replace. Of course, you may be completely wrong! It’s important to test your lists thoroughly every time you make a change, and record your results. Don’t give up after just a few games and swap back either, as sample size is key. Keep playing until you’re sure how the change affects your winrates. With any luck, you’ve just made a good deck that little bit better; at least until the meta shifts again!

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