[Update #2]: MTG Arena's October 13th update will ban The Meathook Massacre from the Standard format.

[Update]: After years of dominance, MTG Arena is nerfing two of the best decks in the Historic format.

As a part of the May update, MTG Arena banned Tibalt's Trickery and Winota, Joiner of Forces from the Pioneer-like Explorer format in order to ensure the metagame doesn't become too skewed towards combo decks. While the bans certainly did help in that regard, they also indirectly caused another problem - the rise of powerful Blue/Red/X decks.

So in ongoing effort to get the formats as stable and balanced as possible, Wizards of the Coast has now also banned Expressive Iteration from both Pioneer and Explorer. While bans don't usually target simple card advantage spells, Expressive Iteration has proven itself to be a remarkably powerful card across a variety of eternal formats, so it makes a lot of sense to get rid of it if the goal is to weaken Izzet (Blue & Red) style decks.

Additionally, Wizards of the Coast has now decided to ban the often-problematic Winota, Joiner of Forces from Pioneer, with the reasoning being that it creates frustrating gameplay patterns for the opponents. Needless to say, this means that Explorer's 'temporary' ban of Winota, Joiner of Forces is now going to be a permanent one.

You can read more about these bans, as well as the status of other formats, over at the MTG website. Enjoy the (hopefully) fresh new meta!