Deck Building Guide

As CUE is a battle game, building (and playing) different decks is at the heart of the game. The two most important principles for designing a deck are energy and synergy. You need enough energy to play your cards and your cards need to have coherent abilities, each contributing to some overall game strategy. As you build and refine a deck, you will need to iterate between these two concepts - maybe there's a card you want to include because it buffs your deck but it's a high energy card and makes the deck unplayable, then you need to find a way to reduce your energy expenditure. Or maybe you are starting with a deck you have previously used but the league rules are different and you need to tune your deck to a different energy level. There are various overall strategies that can be played, each with their own deck archetype and many flavours of decks. The deck ecosystem is very rich, with no overall best deck. Each deck is strong against some decks and weak against others.

## Energy

In league, it is important to play three cards per turn. This allows you to build up the card interactions, bring combos together, and cycle your cards in such a way to take greatest advantage of each card. While this is also true for casual, the energy per turn is so low that building your deck to play 3 cards per turn in the first round is likely to require very low energy cards which have low power and you will not have enough power in later rounds (and a lot of spare energy). This overall goal sets a target average energy per card. There are two components to the rules, the energy per turn and the starting energy. Assume that the starting energy is to be consumed over 15 turns, and add that to the energy per turn. For example, with a starting energy of 50 and 8 energy per turn, you can expect to have available about 11 energy per turn (50 / 15 + 8). In turn, this sets a starting point of average energy per card of energy per turn / 3 (continuing the example, a little under 4).

There are three different ways in which card abilities affect the energy available:

* Energy per turn: Some card abilities directly change the energy per turn. For example, HMS Beagle increases the energy per turn for the rest of the game each time you draw it (so it provides +1 the first time, then another +1 the second time so that the energy per turn is now 2 higher that it would have been).
* Energy stock: Some cards deliver energy directly. For example, Brontosaurus adds 5 to your energy stock without having to play the card. On the other hand, Axolotl gives you 4 energy back after playing it. In both cases, if the added energy would take you over the maximum allowed under the league rules then any excess is discarded, it is not available later.
* Cost reduction: Some cards reduce the energy cost of cards in your deck. A good example is Sons of Liberty, which reduces the cards in hand when you draw it.

All of these change the overall energy equation, allowing you to build your deck with a slightly higher average energy per card than is apparent mathematically. If the energy per turn is lower, then you might need up to three energy cards in your deck but high energy league rules mean no energy cards are required at all. A good starting point is between 0.5 and 1 average energy per card above the calculated available. As you play test the deck, you can swap in cards to balance having enough energy available to play 3 cards per turn with using as much of the available energy as possible (because higher power cards typically consume more energy).

You need to adjust in the other direction if you are playing cards with energy penalties. Some of the largest energy penalties are incurred from A Christmas Carol and Testudo Formation, each of which adds 18 energy each play (assuming you play Testudo first turn of the round) and spread out over the deck, that increases the average cost of your cards by 1 per card, or 3 extra energy per turn.

## Synergy

Synergy is about choosing cards that help each other toward the overall goal. There are three broad ways of winning in CUE.

* Power Difference: The three cards you play total more power than the three cards your opponent plays. This can be achieved by playing cards with high power (referred to as greedy decks) or by reducing the power of your opponent's cards (Debuff decks)
* Power per turn: You build up power per turn (ppt) with cards that individually have low power but their ability adds ppt for the rest of the game (such as Diamond Tetra). By the later rounds, the free ppt adds to the low power of the cards you play to get large enough to overpower the opponent. Be careful not to lose 3-0 though, you need a way to win an early round too.
* Disruption: You play cards that stop the opponent from playing their 3 cards per turn. This could be directly locking the cards so they cannot be played, or controlling energy so your opponent does not have enough energy to play three cards. There are two energy control approaches, draining or reducing the energy store (such as with King Cobra) or inflating or increasing the energy cost of cards (such as with King Midas), Many energy control decks use both approaches are are referred to as drainflation decks.

Many decks focus on some form of Power Difference. They will contain cards that add power to cards that meet some condition (buff cards) and cards that receive those buffs (filler cards). Those conditions might be about deck structure (for example, Heimdall or Statue of Liberty), belonging to a particular Collection or Album (for example Mummy), or referring to base energy, power, rarity or other characteristics (such as Dark Web for cards with power at least 60, Frilled Dragon for cards with up to 2 energy, or Knights Templar for common cards). You need to have enough buffs to build substantial power on each of the target cards, but also enough target cards receiving those buffs.

When building a deck, pick a theme that you want to play. What strong buff cards do you have? Build around those. More advanced decks will have multiple layers of buffing, perhaps using both a structure buff but also choosing cards that fit the required structure and have mutual buffs. When you have picked a theme, understand what makes that theme strong and work towards those strengths. Make sure that cards you add to the deck meet any required conditions.

Some matches are simply slug-fests. Who has made the best choice of what to buff and balanced the buff and filler cards to end up with more power? But pushing your deck to the energy limit makes it very susceptible to Disruption decks. If you can't play your buffed cards, then it doesn't really matter how strong they are. On the other hand, cards in disruption decks have generally weak power per energy themselves, so a good response is Power per Turn decks because it doesn't matter if you can't play all your cards by the end of the game since there is enough free ppt to win anyway. Power per turn cards also have low power per energy so it can be difficult to win early rounds against Power Difference decks.

As a rough guide: Power Difference beats Power per turn, which beats Disruption, which beats Power Difference.

The balance between the different ways of winning keeps the decks diverse. It may not be much fun to play against a drainflation player since you can't actually play, but it would be even less fun if every player was simply trying to build the identical big hitter deck, as happens in some other games.

## Getting in the Way

It's not enough to build the perfect deck, you also need to be able to play the cards in the deck in such a way as to trigger the buffs. There are a few rules of thumb that can help to make the deck playable (as well as thinking about energy).

You have five cards slots and want to play three cards per turn. If you have combos in your deck, then you may need to play those cards together. A good starting point is never to have more than one 3-card combo or two 2-card combos in a deck. If you have more than that then you are likely to not have enough free slots to hold cards until their combo partners arrive.

Many decks have cards that you want to hold for multiple turns (or even all game) because they improve your deck every turn they are in your hand. In general, you can only have one hold card in a deck. If you are holding two cards then the only way to play three cards is to play the cards you draw.

These two restrictions interact. If you have a hold card, then there are only four slots for the rest of your deck and you will have more trouble setting up combos. You can include one 2-card combo with a hold card, but it's generally better to not have combos at all unless they are really important.