Ugin, the Spirit Dragon, for better or for worse, will change everything.
For a long time, Standard has been defined by mana acceleration. Things like Gilded Goose, Growth Spiral, and Uro, Titan of Nature's Wrath have been enabling fast Nissa, Who Shakes the Worlds and Elspeth Conquers Deaths. When cast a turn ahead of schedule, especially on the play, those cards snowball the advantage they create. Hydroid Krasis at the top-end served as a mana sink and a way to never run out of gas.
Those decks were frustrating to play against. "Never be the smaller midrange deck" held true and thankfully that rule may put an end to those decks. There wasn't a top-end that could invalidate what everyone else was doing until now. Four copies of Ugin, the Spirit Dragon will go a long way toward shaking up the format. It will usher in a new normal, and while that new normal might be frustrating, at least it'll be different.
We have an incredible amount of acceleration and a huge payoff, so let's get to work . . .