The game changed quite a bit in the span of a couple hours yesterday, as the implementation of patch 7.9 and the mid-season changes that came with it has tossed the established metagame into the air. Three champion reworks all hit the rift at the same time, Maokai, Sejuani, and Zac, while sweeping itemization changes ensured that even champions that had no direct changes would need to adapt to the new patch. Tanks got more resistances while losing health, ADCs got big changes to the Infinity Edge build path, while mages suddenly found themselves having to contend with Banshee's Veil having 70 AP tagged onto it. In short, everything about the game is pretty up in the air at the moment, and with one exception it's pretty hard to figure out how the chips are going to land by the time things settle down.
That one exception is Sejuani, who didn't just hit the ground running, she hit it sprinting. As we at WWG have been predicting for some time, she's immediately proven herself as one of the preeminent top
Were that all Sejuani could do, though, that wouldn't be enough to call for her to be permabanned, but as anyone who's played against any of Sejuani's incarnations in the later stages of the game knows, things only get rougher for the enemies of Sejuani as the game goes on. She's always been among the strongest teamfighting champions in the game, and even Glacial Prison's nerfs can't change that. Sejuani has always transitioned into an amazing late game tank, but lacked the early game strength to get there consistently. Now that she can lane with the best of them, there's little to stop her from just scaling up and dominating late game, especially since ganking her is extraordinarily difficult thanks to her easy escape mechanism.
So, if you don't have any interest in tangling with a lane-dominating tank who is immune to burst damage, has the damage output to kill carries solo, as well as the crowd control to ensure they can't flee from her, I recommend you utilize the only consistent counter available for Sejuani. The ban phase.
I bid you all good luck in your quest for LP on the new patch. Be sure to report back and let us know what sticks out to you!