The Bant Tamiyo is a great one to highlight, not least because her ultimate just gives you an OmniscienceOmniscience for four mana and additional investments over a few turns to protect her
Storm decks have been given a shot in the arm with the printing of Baral, Chief of Complience, and Rule of Law is perhaps the most powerful card you can bring to the table against a Storm deck
A 4/4 flying lifelinker can swing any damage race, and the final chapter's reanimation ability allows you to flood the board with Modern's best one-drops and two-drops, allowing you to go over the top in grindy matchups
This Bloomburrow commander has incredible snowball potentialspending 8 mana in a single turn means you have, well, lots of mana, so you should be able to cast both spells exiled off Muerra, which increases the odds of getting another two cards to cast the following turn, and so on