See the full breakdown per format in the Legality section above.
Aside from the fact that this is probably the most cataclysmic event the game has ever seen story-wise, it's also the first set in an extremely long time to introduce a new card type, as well as just generally being jam packed full of crazy legends, double sided cards, new mechanics, and more
Tariel requires a lot of work, but the payoff's there
(To proliferate, choose any number of permanents and/or players, then give each another counter of each kind already there.) Illustrated by Wisnu Tan Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Not Legal Brawl Not Legal Legacy Legal Comp
Playing a creature, I'm happy to report, grows your ability to attack and win the game