Some include a physical or vocal component, like Blacker Lotus or the Gotcha! mechanic on Touch and Go, some have rules that specifically reference flavor text or artists, like Carnivorous Death-Parrot and Drawn Together, and some require interacting with people or objects outside the game (Ashnod's Coupon being my favorite)
What are you most looking forward to running from the set
If you look at the makeup of a March of the Machine booster, its very similar the make-up of a play booster
even Roaring Moon decklists which includes techs like Water Energy and Cancelling Cologne (for Radiant Greninja), or Iron Hands ex, tend to suffer from a loss in consistency and arent reliable Gardevoir counters
This area serves a similar role to the discard pile, but is even harder to get cards back from
We will be keeping a close eye on how it affects the format, but for now, we want to see how you cook