To buy or not to buy?

Inspiration card art

With the next Magic set, Core 2021, just under a month away, the preview season began a few days ago.  (The preview season is where Wizards, through their own or independent popular Magic websites, reveals a few new cards per day from an upcoming set.)  A few common preview sites for Core 2021 (which feature overlapping, but not always identical, cards):

• The official site
• MTGGoldfish
• MythicSpoiler
• ChannelFireball
• MagicSpoiler
• Scryfall

As I perused these sites, I am getting excited about the upcoming set! It isn't always so; one thing I enjoy about this game is the ability to collect or ignore sets are you see fit.  I bought a ton of Throne of Eldraine, for example, and almost no Ikoria or War of the Spark. For a given set, I use the preview season to decide, and four characteristics to guide my decision:

1. Theme
• What types of things does the set emphasize? For example, Throne of Eldraine was influenced by Grimm's Fairy Tales and Arthurian legend; Theros Beyond Death by Greek mythology. Ikoria was inspired by the Japanese genre of giant monster films. Though core sets, by design, are more generic than expansions, they still have some discernible theme.  In Core 2021, for example, they're introducing a handful of dog creatures.
2. Mechanics
• Often related to theme are the mechanics. What card types, keywords, tribes, or abilities does the set feature? Eldraine had knights, adventure spell types, food tokens, and the adamant keyword (which encouraged playing only one color). Theros BD featured enchantment cards (and the related constellation keyword), and also encouraged playing one color through the devotion keyword.  Ikoria features card cycling and mutate.
3. Impact on metagame
• I don't know how well they can plan this in advance, but I look at how upcoming cards might change the meta. Containment Priest (below) is coming, for example, and will work wonders against several powerful cards seeing a lot of play in today's meta.
4. Art
• How does the art look? It doesn't affect the gameplay, but the overall aesthetic does matter (to me). Each Magic set (or block, back in those days) has an artistic style or tone appropriate to the theme. 

Theme and art are intertwined, and can be quickly judged ("ooh, Grimm's Fairy Tales? Sweet!"). Mechanics are harder- you may need to play a few games to see if they're of interest to you, unless they're a return of a previous mechanic (like cycling in Ikoria).  And meta impact is hardest of all- even the experts can be wildly wrong about how much play a given card will see.

These characteristics enable me to determine ahead of time whether or not I'll buy a booster box of cards or just get some single cards of interest. Once I saw War of the Spark would focus on planeswalkers, for example, I knew I was out- I hate planeswalkers.  So I bought a few single cards I wanted and stayed away from the rest.  Of course, since some aspects are hard to judge in advance, there are times I initially stay away but then buy in (Theros BD is an example).

Back to Core 2021. I'm excited so far because:

• I like core sets in general; they're usually more 'generic' and basic than expansions, and take me to the heart of the game without being overly complex
• Seeing dog creature cards and tribal themes excites me; cats have had their day for a while now. Time for the dogs!
• I don't care for the current meta, and think a few cards will tilt the game in a way I enjoy.
• They're reprinting some old cards, like Baneslayer Angel (see below). Fun!

If you want to follow the previews, click on any of the links above, they're updated almost daily.