Well, I made some patchwork kit for her. Up for your consideration.
Since you did not give her name, I will just go with calling her granny.
Some of this is based on what use @The Djinn, proposed.
I tried to make it fit "anti-toplane-adc" as I could.
Passive:
Every 14-4 (level based) seconds, Granny prepares a protective coat (visuals would be icicle like strips of glimmering ice on her back)
When she is next attacked, she spins a little, using staff as support, to block 50% of this dmg with her back. While swinging, she can click on any unit within 700 range.
This makes her finish swing with jump, closing on unit selected, this dash does not follow, and its maximum length is 450 units.
This refreshing fun gives her 1% max hp regen per second for next 5 seconds.
Also, since she uses her long staff to attack, her Attack range is 200(
range),
Q:
Active. Medium mana cost. Uppercut slash, creating wave of true ice spikes from ground, dealing moderate damage, and slowing enemy for 30% for next 2 seconds.
As of weapon motion, think of Reinhardt (Overwatch), maybe you know how projectile of Tusk Q looks like.
W:
Active. Enhance your staff. (Visual of Ice growing on her staff). No mana cost. 16-8 second cooldown.
Next time you damage slowed enemy, you will stun them. If its by ability, reset cooldown of that ability. If done by attack, reset aa timer.
This does bonus magic damage for duration of stun. Stun duration is 1.2-2.2 sec, based on level of the ability.
E:
This is ability you proposed. Draws chunk of true ice from ground and hurls it, grounding first enemy hit.
As for animation, if its cooldown is reset by W, and its used again in short window, its animation is changed, where she throws it in more sideway fashion.
Drawing it from ground on her left, doing forward hand motion to throw it.
R:
Granny knows how to instill order in her house.
Active: Granny grabs her staff with both hands, lifts it slightly, then smash it against ground, creating outward wave of ice, spreading outwards for 600 units, stopping at terrain. Animation should be moderately slow, about 0.8 sec long, and wave travel time to edge would be 2.5 sec.
I think she would excel at top, with her passive giving her some defense.
She would be played as reaction crowd controller. In lane, her passive makes ranged enemies wary of poking her, as she can jump on them anytime.
If they decide to just farm, she can harass them with Q. Since she does not boost that much damage, but has some sustain, she would not limp behind some usual toplaners, but still would have problem with most Bruisers.
In team fights, she would also pose tactical threat even while just standing near team. She cannot really initiate first, but with her ult - w, she can retaliate very well. This will either force enemies to try to get around her, leaving her free playground, or burst her down, what can be hard without heavy CC. That would also mean she does her role as tank perfectly.
As for items, she would be one of few I would reccomend
on,
but then there is
for more cc,
or
in case they dont want to go close,
as setup for W-R, capable of stunning whole team.
for pure tank stats, or
to make enemy adc hate her.
for more dmg oriented build.
Thanks for reading.
Hope you are gonna like it. Anyways, awesome concept, keep up the great work! :)