As of now, Oko is only legal in Legacy, Vintage, and Commander (among all of the sanctioned formats he is legal in). Oko is banned in five other sanctioned formats, by comparison.
Nic Kelman: Oko is from a plane ruled by Fey who believe in a unified society, one where the ruling class has decided that for the betterment of all, the natural mischievousness of the Fey has to be suppressed.
To add to this point, in the Project Modern custom format, Opal is unbanned and is not dominating anything even with Urza legal in it. Oko played a huge part in Urza's dominance. I'm also a little salty because we also lost astrolabe in addition to mox+oko so the deck got nuked out of the format.
Opal is not getting unbanned.
Card Text: +1: Put two +1/+1 counters on up to one target creature you control. 0: Until end of turn, Oko, the Trickster becomes a copy of target creature you control. Prevent all damage that would be dealt to him this turn.
“Going forward,” they continued, “Once Upon a Time poses a design constraint in making it too easy to assemble creature- and land-based combinations.” Therefore, they concluded, “in order to facilitate more varied gameplay and mitigate future risk, Once Upon a Time is banned in Modern.”
Black LotusIt has since been banned from all official tournament formats save for Vintage, but even there, it is limited to one copy per deck, compared to the normal allowance of four. The illustration on Black Lotus was painted by Christopher Rush, who was at the time a Wizards of the Coast employee.
Historic. Field of the Dead has been a powerful force in Historic for much of the format's life. While its overall win rate is rarely at the top, its matchups are extremely polarized. In order to bring a greater diversity to the Historic meta, Field of the Dead is banned.
Veil of Summer has no effect until it resolves. It can be countered. A spell or ability that counters spells can still target your spells after Veil of Summer resolves. When that spell or ability resolves, your spell won't be countered, but any additional effects of the countering spell or ability will still happen.
Veil of Summer, which was also a part of Throne of Eldraine, has been banned in Standard, Historic, and Pioneer but remains legal in Modern.
A card, spell, or permanent is historic if it has the legendary supertype, the artifact card type, or the Saga subtype. An ability that triggers "whenever you cast a historic spell" doesn't trigger if a historic card is put onto the battlefield without being cast.
Over the past months, Once Upon a Time has become one of the most played cards in Modern, contributing to several of the most popular and highest winning decks. In order to facilitate more varied gameplay and mitigate future risk, Once Upon a Time is banned in Modern.
Banned in Pioneer: Inverter of Truth, Kethis, the Hidden Hand, Walking Ballista, and Underworld Breach. In a surprise announcement this morning, Wizards of the Coast banned Inverter of Truth, Kethis, the Hidden Hand, Walking Ballista, and Underworld Breach from Magic: the Gathering's Pioneer format.
WHAT IS PIONEER? Pioneer—a new nonrotating format featuring cards from Return to Ravnica and forward. Pioneer is a constructed format and therefore adheres to the following constructed rules: Minimum of sixty cards. No maximum deck size, as long as you can shuffle your deck unassisted.
