Similar to tavern brawl in hearthstone. I’m not currently an active player, and as such many of my decks are often outdated (due to lack of cards or just meta knowledge) which makes it less tempting to come back and play. I think it would help people start playing again if they had the option of immediately being greeted with a few fun and casual matches, instead of realizing they can’t do anything within the next 10+ minutes because they need to put together a deck and quitting. It wouldn’t even have to give you material incentive to play, just working as a warmup is probably enough. Boss battles are fun but they still sort of require you to deckbuild.
Just a thought.