Can there be an LCG (Living Card Game) Tag?
With all of the LCG games (LOTR, GOT, etc.) I think there will be a lot of duplicate questions regarding the idea of this game type for each individual game
No. LCG is a meta tag (data about data). Meta tags are detrimental to the Q&A format on SE. What purpose would an LCG tag serve?
To add to what user1873 has said:
Adding a tag that would, by definition, encompass several games means that those games would not automatically have their game name added to the title of the page.
I think it is to our advantage that for games with more than a few questions that the game tag should be the most popular tag on the question.
However, mentioning that a game is a Living Card Game on it's wiki tooltip text here and linking to other LCG's would be a good thing to do.
I looked for questions marked trading-card-game. At the moment, there are none.
This leads me to think that living-card-game, as a tag for questions that are generally about "living" card games, would be a similarly narrow tag. Fundamentally the only generically-applicable question about LCGs that I can think of is "What does LCG mean?"