I'm starting to wonder if anyone is even reading bug reports. Only other possibility why this isn't fixed already might be it isn't considered a bug but I can't see why it wouldn't be one. I reported Yuumis W not giving a spellbinder stack weeks ago. This is a bug, right? Fix please :)
Yuumi's W is not even considered an ability it is considered an interactable passive. The CD of Yuumi's W goes down to 0 seconds and does not have a mana cost. hence why Sheen Yuumi is not a thing. Would just be broken.
I think you miss the point it isn't for yuumi. Spellbinder stacks based off of allys abilities used near you too. Imagine a karthus with spellbinder that is stacked in just a couple seconds. Annivia, annie, syndra, any AP champion. So yes I do believe it would make spellbinder broken and yuumi as well even if you nerfed yuumi into the ground. She would be used for free spellbinder stacks in the late game.
