We have currently two tags about Magic: The Gathering Arena:
mtg-arena, 8 questions
magic-the-gathering-arena, 9 questions
Obviously, these tags are duplicates; can somebody with ♦ powers merge/synonymize them? Since all 'specialized' Magic tags start with mtg-
I prefer the former.
I have also submitted an edit to the excerpt stating that it should only be used for questions about situations specific to Arena, not just because they happened during an Arena game.