I would like the event IF we had a possibility to reserve offensive monsters. For the first edition of battlegrounds I actually made a spreadsheet and took notes which monsters I want to reserve for attacks, but this was very cumbersome and I dropped it for this one.
Combined with the inability to feed and rank up monsters after the attack phase has started, this is a logistical nightmare.
Also, Battlegrounds amplifies a big problem in ML: The lack of a decent ingame chat. Basically all games that are anything have mastered it yet, except for ML it seems. Why can't we pin messages? Why can't we post messages longer than 10 words or so? How are we to comminicate strategy?
(I know, many clans use external messengers. Mine doesn't unfortunately, and since it's a great clan otherwise I'll have to live with that.)