Glue

Glue is a Magic: The Gathering R&D slang term for a concept or mechanic that helps connect the different pieces of a set design. 
==History==
In Ravnica: City of Guilds, for example, R&D took great pains to build monocolor themes that overlapped the guilds. For instance, green had a strong token-making theme. Selesnya (white-green) used these tokens to build an army and swarm the opponent, while Golgari (black-green) used the tokens as fodder for its many sacrifices. Theming like this was crucial to the set's design, as it helped create cards that could swing in multiple directions (i.e., they were useful for multiple different parts of the set). 
Glue's importance is threefold. First, it creates more flexibility, especially for Limited play. When every card only uses a single subset of cards, less modularity and less strategy are possible. Second, it helps to link different factions together to allow for more deck-building synergies. Third, it gives the design and flavor more depth. Game players like it when they have some options to explain why something may or may not be happening. A game needs to allow different people to have different interpretations.
Taking various game (preexisting) components and then connecting them into a larger group with a new word that refers to them collectively is a feature in Magic, with the historic descriptor being the first example of this. Mark Rosewater refers to this as "batching". Later examples of batching include party, modified, and outlaw.
===Typal glue===
Typal glue is the solution to make typal Limited designs while simultaneously making sure that enough cards are desired by different decks. It ties various creature types together mechanically.
For instance, if Otter cards are only useful to the Otter player in the draft, then draft decks end up too similar to each other, lessening the long-term Limited playability of the set. This was one of the problems with the typals in Ixalan, as the four subtypes had no overlap due to being all hostile factions. This demonstrated that it is key to have something in the set that helps make cards attractive to drafters drafting different creature types or overarching archetypes.
The most famous typal glue is the Changeling mechanic, where a creature has all creature types. It was introduced in Lorwyn and then showed up in the first Modern Horizons and Kaldheim. Changeling also does show up in Bloomburrow, but just on two artifact creatures.
For Bloomburrow, the main solution was "duos". The idea of a duo is that it represents two creatures working together. This allowed R&D to put two creature types on the card, making it attractive to drafters drafting either creature type or drafters wanting to combine two creature types in a deck. In Bloomburrow, the duos are two common mono-color cycles that make use of each creature type twice. This also helped with boosting the as-fan of each creature type. An additional typal glue that was considered in Vision Design for Bloomburrow was "Fellowship". It was an ability that let a player add a creature type to an invisible list that would last till the end of the game. From then on, creatures with typal effects could affect any of the creatures that were in that fellowship list, not just their own creature type. Set Design didn't think Fellowship was necessary and would have added complexity, so it was removed.
==References==
Category:Magic slang
Category:Game concepts