Interesting concept, but the execution could be better.
First of all, what's the point of making your character have the "bind" cc, which currently doesn't exist, and constrain the area they can move in to something so small that they may as well be rooted? I guess it gives some counterplay to her Q+E combo but it doesn't seem like enough to actually justify it not just being a root.
The passive is super cool, reminds me of jousting which is a fantasy not really touched upon currently in the game. (Kled tried and failed imo.)
To Be Slain seems unnecessary. Q is already super strong escape prevention AND its duration can be reset. If you want her to be that sticky you need to take a chunk off her bases/scalings. If you want to keep it I would suggest changing it to slow the target rather than speed up your team. (Its a lot more balanced to debuff one target than to buff four. Or have it be a mark that can be procced by teammates to grant them movespeed rather than just giving it to them for free. Really push the cooperative elements.)
The damage on Q is absurd considering it is aoe and essentially hard cc AND she can proc at least the damage multiple times rapidly due to the charge system. It's free setup for her passive true damage already considering its long range, it doesn't need to have that much base damage/scaling itself.
Conversely, the W feels unimpactful. I know you don't want to bust into sejauni territory, but the fact it only crowd controls people at the sides(?) of her as she moves is strange. Considering it would be measured with a hitbox, unless they walked into you they wouldnt hit your side. Why not have it do the damage and knock all enemies hit to the side? It's not actually that fast, again interacts favorably with her jousting-esque passive, and has a lot of potential. Consider not locking her movement to a direction because right now it'll never hit anybody unless they have been "bound", and even then they could likely sidestep it. Also consider letting it refresh her passive immediately since it's sort of a charge.
E: I like the synergy, it's simple but not boring. Recast feels like it would be messy though. Have you considered just having it reapply the damage in the "bound" area and refresh the duration instead of that throwing around stuff? It would be much easier to balance. Maybe it could reapply/apply bind to all targets in the area instead of just the one, make it a little more urgent for people to be bodyblocking the spear after lane phase.
R: I like this one a lot. The movespeed fits better here than on her passive, it supports her fantasy of being a combat support person. Recommend shifting some of the damage/scaling from her Q into the spear.
How close must a target outside of the direct impact be to not be knocked away? Plus since it knocks people away it kinda defeats its whole "spin for heavy damage" thing which already requires an ally to touch it to activate.
Right now her Q is super cool but it feels like the rest of her kit is essentially useless if she can't land it. Rather than having so much power injected into that spell, I tried to make suggestions that would make her all-around more functional and enhance her teammate-helping brawler theme. I think you have an interesting direction and the effort you put into the design shows!
