While the local community is still gearing for its first local Pioneer tournament, Wizards has announced last week that the first B&R (Ban and Restricted) update will be Monday. That is today as of this blog posting. We have somewhat prepared the decks, but also speculating what cards are to be banned. That is given that the impactful cards somewhat has a similar effect like in Modern.
Upon checking this morning’s post from the official Wizards website, they have decided to ban Felidar Guardian, Oath of Nissa and Leyline of Abundance. They have explained the reasons behind the banning of each card in the post. Felidar and Saheeli is the best combo there is, existing in the format which would be the center of concern of the other decks in stopping it from going off. This, in turn, affects the deck-building strategies which the WotC are trying to avoid.
As for the Leyline, they are trying to prevent explosive openings in the terms of mana ramp on Green devotion decks which will turn out to be unfair in gameplay.
In the case of Oath of Nissa, it is a cantrip card that also fix mana for early deployment of the three-mana planeswalkers. I am not sure how they justified the banning of this card but they said it will result in a deck archetype that will affect the diversity of other decks in Pioneer.
You can check the full B&R announcement post here.