A Suggestion from a Sejuani fan that doesn't feel like she fits into the meta
Her biggest problems right now is that she gets counter-jungled way too hard, her autoattacks are miserable to lane with, she isn't an especially defensive heavy tank and her damage was overnerfed to the point that she isn't a good initiator outside of the hard cc of her ultimate. Her only strengths at this point lie in her cc and utility but Rammus, Nautilus and Amumu all do her job more efficiently from the jungle.
After thinking about it, I feel that a small change would make her fit better into the support role. The cooldown and mana regen from support items would benefit most of her abilities as well as health from thinks items like locket. If you changed her pathetic w to a shield of some sort (like with Nautilus or Thresh) she could be a good tanky peeler and find a better niche in the support role.
