As of Thursday, May 20, the card Thassa's Oracle is to be banned in Magic: The Gathering - Arena's Historic format, per Wizards of the Coast.
"While Thassa's Oracle is a powerful card that has created combo decks across multiple formats, until recently, it wasn't a force to be reckoned with in Historic," says WotC's Jay Parker. "However, with the recent printing of Tainted Pact and the fine-tuning of that archetype, we've seen the rise of the two-card combo in Historic to the point that half the field for the past League Weekend utilized the combo."
Between the two cards, the company identified Thassa's Oracle to be the issue rather than Tainted Pact.
"Due to the power of the two-card combination, and because we expect that Thassa's Oracle is likely to cause problems down the road as Historic continues to add new cards, Thassa's Oracle is banned in Historic," Parker adds.
Wizards of the Coast announced no other changes at this time to the Magic: The Gathering banned and restricted lists.