Thread by @Sierkovitz

Long Data thread ahead! With first data from STX starting to pour in @17lands, I thought to take a deeper look at Lessons and Learn spells. The new mechanic is definitely powerful, but so far we never dived deeper into what is great and what is not so hot about it. 1/21

@17lands Today I will focus on the lessons, with learn spells soon to follow. First things first: Lessons are all about diversity and ability to draw them. Here you can see win rates based on how many unique lessons deck has in SB and how many learn cards they have. 2/21

@17lands As you can see there is a strong correlation between those values and win rates. Lessons give a deck flexibility to answer more threats, solve more issues with your deck. At the same time, learn spells allow you to use Lessons when need arises making them more powerful. 3/21

@17lands But not all Lessons were made equal. Let's start with the frequency they are learned. This graph shows in what percent of games these were in the sideboard, where they drawn into the hand. As you can see, Mascot Exhibition is a clear leader. 4/21

@17lands It is not-so-closely followed by 4 of the 5 Summonings, then there is a large peleton of colourless common Lessons with the remaining Spirit Summoning, uncommon black removal and green and blue rares. Far behind is the rare black PW removal/reanimator. 5/21

@17lands But frequency of drawing tells us little of the quality of the card. This graph shows how does each Lesson improve win rates when it is drawn from the SB vs the games it is not. Here you can see the true power of Mascot Exhibition. 17%p increase in win rate is massive. 6/21

@17lands But apart from this clear bomb, there are some cards that would have been surprising before STX was released. Expanded Anatomy with 10%p increase in win rate is somewhat impressive, so are 3 of the summonings: Inkling, Elemental and Fractal. 7/21

@17lands All of those cards are learned frequently (30-55% of the games). But they are followed by more niche Lessons. Start from Scratch, Illuminate History and Academic Probation are learned ~10% of the time but when they are, they give a reasonable boost to your win rate. 8/21

@17lands One surprise is a relatively low impact of Environmental Sciences. Only 1%p increase is very modest for such commonly learned Lesson. Even worse news for Necrotic Fumes, Intro to Annihilation and Pest Summoning. Learned >25% of the time they reduce win rate. 9/21

@17lands Keep in mind, that very situational Lessons like Start from Scratch will be very good when useful, but since they are rarely useful, their impact on general win rate will be proportionally lower. 10/21

@17lands Card useful 10% of time, even if increases win rate by 10%p when drawn will only increase your general win rate by 1%p. Cards learned frequently (say 50% of the time) will have the same impact when they increase win rate by only 2%p. 11/21

@17lands But the data so far is far from the whole picture. Power of Lessons is in their flexibility. Let us return to Environmental Sciences. Just having it allows you to build a deck differently. Splashing is easier, mana screw is less scary. 12/21

@17lands In games where you drew perfect mana there is no need of finding it. On the other hand when you really need it, it means something wrong went with your hand. This puts this 1%p increase in win rate in a different light. 13/21

@17lands A deck with Environmental Sciences (and learn) will be strictly better from the exact same deck without. I tried two approaches to try and see this effect. Neither method is perfect, both have some issues and should be treated carefully, but they point to some answers. 14/21

Firstly, there are two possible reasons for not learning a spell: you chose not to (played a learn spell but chose another option) or you couldn't (no learn spells available). I looked at those two scenarios. 15/21

First striking find was that there is a negative correlation between win rates when chosen to draw and chosen not to draw. Cards that do poorly, are in decks which have high win rates when other Lessons are selected and vice versa, decks do bad if you pick a low wr lesson 16/21

This can have two explanations: either Lesson is poor, or is only useful in desperate situations in case of worse performers, and you only chose not to draw it if you are in bad situation in case of good Lessons. Win rates when you couldn't learn were low across board. 17/21

Last method was (for now) only applied to colourless lessons. I looked at the win rate of decks with and without access to those Lessons. Since they have no colour requirement, if there is a win rate difference, it can be a proxy for Lesson strength. 18/21

Again, Mascot Exhibition was peerless. But all the colourless Lessons had impact on win rate. Especially the 1.8%p increase in decks with access to Environmental Sciences can give a peek on the cards real power. 19/21

Be aware, that even though colourless, some of those Lessons may be better in one archetype, but it should still be a good indicator of generic Lesson power. To conclude: Lessons are powerful, some more obviously than others. 20/21

Data can show you a glimpse of that power but use your limited skills to hone on the perfect recipe rather than taking these values as the end of discussion. And let me know if you have any questions or suggestions! As always, thanks to @17lands for all the opportunities. 21/21

@17lands CC: @Chord_O_Calls
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