A lot of players seem to believe that in order to make Snecko eye a good choice of boss relic, the deck should contain high-cost cards. They are hesitant to pick this relic up. The thought is that snecko eye changes the costs of cards to 1.5, and that therefore, compared to an energy relic, the snecko eye makes a tradeoff:

  1. You get more cards to choose from;
  2. Cards cost 1.5, so you can play less cards than without it when your cards are mostly cheap. So 2 cards per turn seems to be what you can do on average.

In addition, everything can cost 2 or 3 sometimes, allowing you to play only one card. Therefore, Snecko should rarely be picked, especially without 2-cost cards.

Is this assumption correct?

1 Answer 1


This assumption is actually mostly wrong. While indeed the average card costs 1.5, the cards are randomly distributed. By increasing your hand size to 7, it is likely to see multiple zero- and one-cost cards. This little piece of C# code tries to simulate how many cards are playable with 3 energy, on average:

int numCards = 7;
int[] costs = new int[7];
Random rand = new Random();
int totalPlayed = 0;
for(int tries = 0; tries < 1000000; ++tries) { 
    for (int i = 0; i < numCards; ++i) {
        costs[i] = rand.Next() % 4;
    int avE = 3;
    int cardsPlayed = 0;
    for (int i = 0; i < numCards; ++i) {
        avE -= costs[i];
        if (avE < 0) {
        } else {
    totalPlayed += cardsPlayed;
Decimal avgPlayed = (Decimal) totalPlayed / (Decimal) 1000000;
System.Console.WriteLine("AVG cpt: " + avgPlayed);

One million hands are simulated. Try running the code: It should print out a figure of about 3.83.

This means that, if you don't draw any additional cards, Snecko eye allows you to play 3.83 cards out of the 7. If your average card cost used to be 1, then that is a distinct improvement over the 3 cards you could play before Note: adding both 0 and 2-cost cards to the starting deck can increase the played cards as well via the same mechanism, to around 3.2 cards at most in typical games.

A pure energy relic would up the number to '4' cards. The break-even card cost (where Snecko eye does not increase or reduce) is thus at an average cost of around 3/3.83 ~ 0.78. For a mix of 20 1- and 0-cost cards, this would mean at least 5 zero-cost cards.

Here's what the probability distribution histogram of each number of playable cards looks like:

Snecko historgram

  • 1
    I am not convinced. I would always avoid Snecko Eye relic, unless must (e.g. if I go for a certain strategy and got several energy expensive cards, then I may decide to switch to snecko-style). Anything what is luck based brings uncertainty, you don't want all your defensive or important cards suddenly cost 3 energy during boss fights.
    – user135338
    Commented Jul 16, 2020 at 15:04
  • It might be better to include a graph for that, showing what the chance of bad luck (less than 3 cards playable) is; to see how big the variance is. Done this.
    – aphid
    Commented Aug 13, 2020 at 8:13
  • I disagree that an average cost of 1 necessarily means you can play an average of 3 cards - it depends on the cost distribution. Suppose you have a deck containing an equal number of 0- and 2-cost cards, for an average cost of 1. With a hand of 5 cards, going from all 0-cost to all 2-cost, you can play 5, 5, 4, 3, 2, or 1 cards. The 0/5 and 5/0 split pair up as equally likely for an average of 3 cards, the 4/1 and 1/4 split pair up for an average of 3.5, and the 2/3 and 3/2 split pair up for an average of 3.5. The average number of playable cards is closer to 3.5 than 3 in this case. Commented Apr 8, 2022 at 15:53
  • @Nuclear Hoagie This detail is true, I didn't consider the same effect when you add a bunch of 2/0s to the starting deck. (Though the example is a bit pathological; most decks tend to have 7-9 1-costs, and maybe around 5 cards added to it by the start of act 2; some of which are typically also 1-cost. But I'd guess around 3.2 is possible to achieve. I took the number to be 3). Question assumes you just have 1-costs though.
    – aphid
    Commented Apr 11, 2022 at 7:06

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