[Update #2]: MTG Arena is getting the Commander focused Battle for Baldur's Gate set on July 7th.
[Update]: MTG Arena's May 12th update has once again banned Tibalt's Trickery and Winota, Joiner of Forces, though this time in the Explorer format.
Ever since its arrival in the Zendikar Rising set, the four-color Omnath, Locus of Creation has been nothing but trouble. At one point it had such a stranglehold on the Standard meta that Wizards of the Coast moved with previously unseen speed in order to get it banned.
Eventually, with the appearance of the digital-only Alchemy format, the Arena team figured it's finally time to give Omnath another chance... though in much less powerful form. As it turns out there is a very fine line between a card being insanely overpowered and almost irrelevant, and unfortunately for Omnath, its new incarnation ended up firmly on latter side.
For most cards this would be the end of the story, but Omnath appears to be so popular that Wizards of the Coast have decided to give it a third chance! As such, thanks to the May 5th Alchemy Update, Omnath's "scry 1" has been changed back to "draw a card," though its increased mana cost still remains. While I don't know if this will make it powerful enough to dedicate an entire deck to making it work in either Historic or Alchemy, I have a feeling this freshly rebalanced version will at the very least be quite potent in Historic Brawl!
Omnath is back?
Besides poor ol' Omnath, the May 5th update has also nerfed two overperforming black cards: Citystalker Connoisseur and Painful Bond. The first is no longer able to snatch lands out of the opponent's hand, while the second now causes cards with mana value 3 or less (rather than more) to ping you for one damage upon being cast.
There's also a variety of changes to a mishmash of different cards, none of which seem to share any sort of theme. So if you're interested in all of the details, you can find what you seek over at the official patch notes.
The final thing worth mentioning is that Wizards of the Coast has now launched a brief all-access event. So if you want to try out some of the new changes, or even just a Standard deck you are fancying crafting, this event is a great place to do so since you don't need to own any of the cards.
Have fun, and I'll make sure to let you know once the next big update arrives!