A Silly Sej Suggestion
Right now Sej's passive on the PBE is that for 3 seconds after taking damage, it makes her immune to slows and gives her bonus armor/mr. However, if you look at Sej's medium rework, riot's goal was to encourage her to be picked and played around melee champs. So why doesn't Sejuani get a passive where she gets bonus armor and mr that scales on melee champs around her, and that when she uses a skill, ally melee champs around her get a 3 second armor/mr buff that's half of whatever she gets from her passive and her whole team gets a decaying MS buff.
I know how much riot hates auras, but this idea would fit in better with Sej's rework and would allow her to multiply melee based teams better. If Sej is supposed to be a calvary leader, then this idea would give her a ton of utility that she's lost from her CC nerfs.