Taliyah Worked ground
I never played a champ that has something in their kit that works so much against them. Firstly let me talk about an issue that I know Taliyah player's face which are tanks. The recommended build wants you to get Ryla to make her Q useful and other hybrid tank mage items but you really cant not afford to do that on Taliyah since she ends up barely doing damage, and even when you build a ton of AP, still struggle to kill tanks late game.
Her E-W combo is her main burst but W has a high cool down for it to be effective so once you used the combo once in a team fight you rely on your Q. Her worked grounds is bad in team fight in lane, and even worst in team fight that are in the jungle. You use your Q and that takes up a whole jungle path so now you ether have to move forward or backwards out of your worked ground to use the full Q again, which plays so much against you when considering it forces you to unnecessarily position yourself.
I had Deathcap- voidstaff- ryla- ludens echo-- morelo- sorc boots- and my full Q tickled tanks, then i have to worry about re position because if i dont, i land one flimsy Q. Even my E-W combo does not do satisfying damage to tanks even though i have all this penetration and ap heavy items. I understand Q can not be allowed to do a ton of damage because it has such a low cool down and it would be ridiculous if you can constantly do massive burst with your Q. My main issue is worked grounds, you get an insignificant speed boost from it and mana refund, but that doesn't outweigh the downside of it constantly being inconvenient and being something you have to play around and something your opponent benefits from.
My suggestion is to make Taliyah Q kind of like Khazix ultimate in which you activate it to shoot a singular shard and can reactivate it to shoot more shards for a maximum of how ever many shards. Each single shard cost certain mana, and after not using for however many seconds it goes into cooldown or after how ever many shards have been fired it goes into cooldown.
As for worked ground, should be something like Taliyah can ride her board on worked grounds regardless of champion or minion damage.