TLDR: No Changes at this time
Panoptic Mirror 
We’re still working on some decks with this card. Our internal playtesting has shown this card to be fine, though we want to be cautious about releasing anything that is currently on the banned list. We are holding off on a final decision, pending further testing. We will continue to test this card internally and provide an update at our next announcement.
Professor Onyx /Chain of Smog 
This combo has been strong, but not any more overwhelming than any of our other competitive tier decks. This is still on our radar. For the time being, this combo remains legal.
Jeska’s Will 
The power level of this card is very high. In Oathbreaker, where it can be the Signature Spell, allowing it to always have the “bonus”, it may be too powerful for its mana cost. We’re keeping an eye on it.
Dungeons are not cards in the traditional sense. They function in Oathbreaker in much the same way as they do in Commander.
Modern Horizons 2 / Adventures in the Forgotten Realms
These two sets have given us a wide range of new cards. Nothing has immediately hit our radar as worrying, but we will see what we find as we add the new cards to our decks and play magic.
Our next announcement will be on October 22nd.