I expect Thalia, Heretic Cathar to be included in a lot of decks early in the format, and she eventually could be removed or relegated to sideboards once the metagame shapes in a way that is hostile to creatures without abilities when they enter the battlefield
Summer Magic: Summer magic was intended to fix a whole bunch of printing errors from Revised
Multiple mythics are already preselling for almost $20 each, and a couple of them look poised to slot into the respective tier decks without blinking
Guide looks like an energy card, and it is, but its also just a Soul Sister that dumps a bunch of extra evasive power into play for free after a few turns
One of the first decks many people think of trying in Commander is a five-color deck with a bunch of planeswalkers
The Cursed role can be a good way to weaken another players creature, and I think theyd work really well in a Toxrill, the Corrosive deck