I only have 1 official mass deck, which is "pink haired characters I don't know but think are cute." Unofficially I mass deck a lot of my favorite series, I just don't put them into separate sections on my post or anything because I'm too lazy for that. I love seeing other people's unique mass decks though, like not series-specific but random themes like animal decks or funny deck names or whatever.

Taking cher15hed19, agoraphobic17, souledge19, thecalm17, uffda18, plans04