The Basics of Sideboarding

Sideboarding is a very critical skill for Tournament players, and is often the difference between winning and losing the second and third games of a match. However, its also a very difficult skill to acquire, as at this time Eternal is only played Bo3 during fan tournaments like the Eternal Tournament Series. This guide will help to introduce you to the basics of sideboarding, some of the strategies you can use, and help you avoid the basic pitfalls players often fall into when sideboarding.

What is a Sideboard?

In the ETS, a sideboard consists of 15 cards. After the first game of a match, you are allowed to use these cards to modify your main deck, adding some cards from your sideboard and removing some from your main deck in order to ensure you maintain a legal deck.

In Eternal, most players sideboard by creating a 90 card deck containing all the cards in their main deck and sideboard. Then, when it comes time to sideboard, they duplicate this deck, then remove cards they don’t want until they have 75 cards. This has the added bonus of helping you to consider all your cards every time you sideboard.

What are the general goals of Sideboarding?

Specific sideboard strategies and plans vary from deck to deck and from player to player, but a few basic rules remain. The golden goal of sideboarding is to improve your chances of winning the match. You can do this in a number of ways:

  1. Cover your deck’s weaknesses
  2. Adjust your deck’s curve
  3. Remove unwanted cards
  4. Exploit the opposing deck’s weaknesses

Cover your deck’s weaknesses

This is one of the sideboarding strategies that beginning players are most familiar with. In order to cover your deck’s weaknesses, you bringing in cards that are effective at stopping those weaknesses. For example, let’s say you’re weak against aggressive decks. You might bring in Lightning Storm to stop a flood of aggro, or Combrei Healer as a solid blocker, or Suffocate as additional early removal. Alternatively, you might be weak against Harsh Rule. In that case, you could bring in Sabotage to discard it, Stand Together to block it, or Unseal to counter it. In all these cases, you’re bringing in a card designed to specifically counter that weakness.

A commonly understood example of this is with Relic removal. Most decks do not play high value relics, so its not important to have access to Relic removal in the main deck. However, against those that do rely on Relics, it can be crippling to remove them. This can be especially effective against Relic weapons, especially if you lack the ability to easily remove them.

Adjusting your deck’s curve

This is another sideboarding strategy that is well understood, but only half as well as it should be. We’ll start with the commonly understood example – as a control deck, lowering your curve against aggro. When a control deck faces an aggressive deck, its goal is to survive and run the aggro deck out of cards. Therefore, it doesn’t need the huge top end cards it usually plays – they often get stuck in the hand and the game is over before they get a chance to play them. Therefore, they board out their more expensive cards and bring in their cheaper removal and blockers to help them stay alive. Midrange can also employ this strategy against aggro, if it so desires.

However, there’s also another way to use this strategy – moving your curve the other way. Most commonly employed by midrange decks against other midrange decks to “go over the top” with an expensive but effective threat – something that will break through a board stall or win the game on its own. Common examples of this include cards like Vodakhan, Vara, or Sky Terror. Aggro decks can also employ this strategy with “finisher” type cards, cards more expensive than those they usually play that can help them end the game when they run out of gas. These will help them smash through for the final points of damage when they run into a midrange deck that stalls their aggression.

Remove unwanted cards

One of the most important goals of sideboard is to remove cards that you don’t want against the other deck. The most common example of this is cutting removal spells that aren’t effective against your opponent’s deck, but this could also be applied to other strategies like curve adjustments or cards intended for other matchups, like maindeck Combrei Healer. The idea after sideboarding is to make your deck as effective as possible, so its important to also cut the cards you don’t want. Of course, this means when deckbuilding you need to make sure you have good cards to bring in as well, otherwise you’re just exchanging one card you don’t want for another.

Exploiting the opposing deck’s weaknesses

This is the most complicated and advanced of the three basic strategies, and also the most difficult to build in advance. While it is possible to imagine what kinds of weaknesses and curves your deck will have, its more difficult to plan to exploit a weakness without targeting a specific deck – which is a high risk strategy, considering you may not face it all day! Exploiting a weakness is more something that is discovered once you’ve seen your opponent’s decklist – perhaps they have few answers to fliers, or relic weapons, or multifaction units. Whatever the weakness is, if you can set up your deck to take advantage of these weaknesses, you should do so. This sideboarding strategy often plays into the game plan you’re using in order to defeat your opponent.

Common Sideboarding Pitfalls

Sideboarding Too Many Cards

One trap that players often fall into is just bringing in too many cards. They have a ton of cards they want to bring in, so they cut more and more maindeck cards… suddenly, the deck doesn’t function as smoothly as it did before. You start getting stuck with sideboard cards in hand – you’ve got 2 Ruin, but they haven’t draw their Azindel’s Gift yet! While it is important to bring in your powerful and impactful sideboard cards, it is important to realize that some are only marginal upgrades, and be mindful of removing too many maindeck cards that make your deck tick. For example, if you cut all of your 1 and 2 drops for high cost cards, you’re going to have a very difficult time getting a fast start. Alternatively, if you cut all your finishers for more removal, aggro may just outlast you anyways because you lack a way to end the game. Bring your cards in by all means, but make sure your deck still runs on all cylinders while you do so. Aggro decks are most guilty of this, but it can happen to midrange and control decks as well.

Sideboarding 8+ Relic Removal

This is another pretty common pitfall – players aren’t sure what to sideboard, so they put a ton of Relic Removal in their board. “If they play a relic, I’ll be ready!” they say. Then, they face a deck with 4xXenan Obelisk and no other relics, and they bring it all in. Then they die with Relic removal in hand, uncooperative opponent having drawn 0 Obelisks all game.

The simple fact is, you’re never going to need more than 4 Relic removal cards in your sideboard against anything. There is not deck in Eternal based heavily enough on relics to make it worth it – the most focused, Armory, usually plays 12 or fewer. Additionally, relic removal is often uncastable if a relic is not in play, which can easily land it stranded in your hand. Finally, relic removal isn’t very good in the majority of cases people bring it in – it is by nature reactive, and having 4xremoval against your opponent’s 4xPermafrost is not a winning strategy. Relic removal can be a powerful tool, but it is important to note that it is quite situational and to avoid overloading on it.

Sideboarding to beat a card, not the deck

Players often tunnel in on a specific card that beats them, especially if they lost to it recently. Relics often create this response, especially powerful ones like Obelisk and Azindel’s gift, but can also happen with powerful units like Icaria. While it is important to have a gameplan against these sorts of cards, it is equally important not to overcorrect when sideboarding. As a general rule, you should never bring in more answers than your opponent has threats – if they have 2 gifts, don’t bring in 6 hate cards. It’s also easier to avoid this pitfall if you sideboard general answers rather than specific ones – you may get more value out of the specific answer, but its also higher risk if they don’t draw the card you’re answering. As always, you need to keep the speed of your deck in mind – bogging yourself down with reactive cards may end up hurting you, because it slows your clock enough they can beat you without the card you’re trying to answer!

Too many cards that do the same thing

This category plays into both the first and the second category discussed above, but in a more general way. When building a sideboard, it is important to give yourself options. When you have too many cards that are only good against one specific deck, you’re limiting yourself against everyone else and liable to Sideboard Too Many Cards against that deck. Look for a range of options, and try to pick cards that are useful in more than one situation. If you have a couple of cards for aggro decks, a couple for midrange, and a couple for control, you’ll be much better set up than if you have 10 cards against control, for example.

Low Impact Sideboard Cards

This is the hardest section to objectively quantify and identify. However, its also one of the most dangerous traps to fall into since it may not obvious, especially without playing the matchup in question. The danger here lies in stocking your sideboard with cards that are only slight upgrades to your maindeck cards. The strength of sideboard is in covering or exploiting weaknesses and expanding the range of your deck. Building a sideboard with cards that do what your deck is already doing, but maybe a little better against some opponents, is not a good way to go about it.

An example – let’s say you’re playing an aggressive Rakano deck, and your Steady Marshalls are getting outclassed too quickly. Swapping them out for a larger 2 drop might give you slightly more board presence (while also slowing down your deck) but it doesn’t address any of the problems your deck is actually facing – your opponent’s units are larger and you need some way to break through. Instead of having those 2 drops in the board, you could have cards that address the actual problem.

Paying no attention to power

Oh, those damn control decks! I’m going to bring in all my 5 and 6 drops as a 25 power aggro deck! Wait, why aren’t I able to cast my spells on time?

When you’re planning on changing the curve of your deck, you also need to pay attention to the power base of your deck, and ensure that you’ll be able to actually cast the cards you’re bringing in. If you’re lowering your curve, you may want to cut a power source or two to ensure you don’t flood out. If you’re raising it, you’re going to want more power sources either in the main deck or the board. If you’re bringing in Icaria, please ensure you can actually cast the card.

This is mostly a deckbuilding flaw – look at your sideboard as well when determining your power base!

Common Sideboard Cards

The following cards are commonly played as sideboard cards and good places to start looking when building your sideboard.

Relic Hate

Proactive Disruption

Anti Aggro

Anti Midrange

Anti Control


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