Citation :
The other noteworthy ban comes for Legacy, an eternal (non-rotating) format that prioritises high-powered play that is more constrained and moderated than Vintage. In it, the Modern Horizons 2 card Ragavan, Nimble Pilferer is being banned, just because it was too powerful.
Ragavan does everything. It only costs one red, but when it deals combat damage it gives you a treasure token and exiles the top card of their library to let you play that turn. As Wizards puts it, "early mana and card advantage can take over a game even more so than in other formats". Ragavan helped games end before they'd even really begun, especially in the format-dominant Izzet (red/blue) Delver decks.