The graphic they added to the Mystery Booster packs had a square background, and the one they used for The List seems to have a rounded background, which creates a telltale difference in the shape of the cards border as you can see on Chatter of the Squirrel and Ancient Den as well as subtle changes in its placement on new border cards, as seen on Boros Challenger
As of writing this, it available for Windows, MacOS, and in the App Store and Play Store, but it cannot be played on smart phones (only on iPads and Android tablets)
It will improve over time as our models are trained on more data
You can only partner these commanders together, as the text says PartnerCharacter select
Tournament Arc: The Genex Tournament in the second half of Season 2
For example, Marionette Apprentice will enter the battlefield as a 1/2 creature, then its fabricate ability goes on the stack