Monday, February 21, 2011

Card-Knapping: Parasitism and Linearity

One of the concepts that came up a lot while I was designing a (mock) Magic set during the Great Designer Search 2 was "parasitism." The designers working on the project were very worried about parasitic mechanics, but there was some disagreement about what parasitism actually is.

To explain parasitism I really need to start with the distinction between linear and modular mechanics. Magic's head designer Mark Rosewater explained it in his article, but I'll try to boil it down in my own words. Linear mechanics strongly imply a certain type of deck. For instance, Slivers encourage you to play with more Slivers, and Morph cards encourage you to play with other Morph cards. Modular mechanics are flexible and can be used in many different types of decks. Examples of modular mechanics include Equipment and kicker. From a design standpoint, linear mechanics are useful because they help to guide players in their deckbuilding choices. Modular mechanics reward more experienced players by allowing them to assemble unique decks in combinations which were not anticipated by the designers. Generally, cards exist on a spectrum of linear to modular.

Parasitic mechanics generally fall into the linear end of the spectrum. However, you can't identify a parasitic card just by looking at it. Parasitism is all about context. For example, here are two cards. Both of them are clearly linear, but only one of them is parasitic:

These cards are very similar to each other. They are linear, rewarding you for playing with a lot of Elves or Allies, respectively. However, only one of these cards is parasitic, and that's Oran-Rief Survivalist. Why? There have been 252 Elf cards printed in sets from Alpha all the way to Mirrodin Besieged. There will doubtless be more Elf cards printed in the future. However, there were only 30 Allies printed in two sets in a single block, and there is no reason to think that there ever will be any more.

So, now we know that parasitic cards are linear cards that only "play nice" with other cards from their set or block. Kamigawa block was probably the most notorious when it came to parasitic mechanics. Rosewater lamented the parasitic nature of the "splice onto Arcane" mechanic in particular. If those cards had read "splice onto instant" instead, people would probably be playing them to this day. However, it was feared by some within R&D that splice would be too powerful if not limited to interacting with a few cards.

R&D still uses parasitic mechanics to this day. Sometimes they just put a handful of parasitic cards into a set to emphasize the set's themes, as with Champion's Drake. Sometimes they use a parasitic mechanic as a major set theme, as with the Ally creatures from Zendikar block. Sometimes the cleanest, most-effective implementation of the gameplay experience R&D wants player's to experience necessitates a parasitic mechanic. Parasitism is sometimes a necessary evil.
A parasitic mechanic doesn't have to stay parasitic, however. Look at Slivers, a parasitic mechanic that appeared on a handful of cards in Tempest, but which have returned in several sets and have appeared at the highest levels of play in every format over the years. There's no telling when the next "Slivers" will explode onto the scene, so for R&D to avoid using parasitic mechanics out of timidity would be a great tragedy, possibly stifling something truly excellent in Magic's future.


  1. I'm so glad you worked "knap" into your column title.

  2. Everyone complained so much about my excessive use of the word knap during the GDS2 that I couldn't resist!

  3. Thanks for helping clarify the difference between linear and parasitic. I encountered a lot of confusion between the two during the #GDS2.

    This line, "Parasitic mechanics generally fall into the linear end of the spectrum," makes me curious: Are there any examples of a parasitic modular mechanic? The two seem mutually exclusive to me.

    I would argue that parasitic cards and mechanics are dangerous, but not inherently evil. Like all things, there is a cost and a benefit to parasitic design and a balance must be reached between too much and too little.

    The cost of a parasitic mechanic like poison or allies is that those cards will not often be combined with new cards in new decks. The benefit is a unique play experience that is generally suffused with flavor, making the set it belongs to feel distinct and worthwhile.

    Too much parasitism hurts the multi-block constructed formats that block lives in and may reduce the desire to revisit it again years later, but too little parasitism can leave the block feeling dry or generic.

  4. Jay,

    A card like Break Open is modular because it doesn't provide any guidance for deckbuilders. I would argue (and I could be wrong here) that it is parasitic because it doesn't function outside of an extremely narrow context (Onslaught block).

  5. We're clearly operating on different definitions of modular vs linear. My definition sees Break Open as a linear card because it interacts only with other cards that share its mechanic--even if the name of that mechanic isn't printed on the card.

    On the subject of morph, I believe it's a mechanic that straddles the line between linear and modular: Many morphs are entirely playable on their own (with their morph costs being profitable useful abilities in and of themselves), but you don't get the bluff effect unless you play more than one.

    Do you consider Plague Sliver modular or linear? I see it as a linear: A Sliver that interacts with Slivers. I don't find the location of those slivers (in your deck or your opponent's) relevant to its classification. But perhaps in your definition it's modular because you can put it in any deck?

  6. I think that because Break Open only works on your opponent's Morph cards, it doesn't encourage you to build any particular type of deck around it, so it is modular.

    I consider Plague Sliver to be modular. Most Slivers are linear, because they are designed to encourage you to build a certain type of deck, but Plague Sliver actively discourages you to from putting it into a Sliver deck. That leaves you with hundreds of potential deck archetypes to choose from.

  7. I suspect Plague Sliver was technically designed as a "silver bullet", putting it much more in line with concepts of linearity. Yet because it's simultaneously an efficient beater, you have an end result that's actually modular.