After thinking for a little, I have some specific clarification questions/ideas for you:
1) Her passive might want to have a wider variety of enemies to activate on. Mainly because you aren't going to be fighting champtions in melee very often. Maybe make it work against any enemy with a debuff?
2) Her W is nifty and goes well with her passive, but it seems limited to me. Maybe armor and Magic resist? regardless, it's a nice ability.
3) Her ult needs some more detail. How is travel time worked out? And, where are the champions pulled together?
a) Maybe on the first champion hit? That might allow some interesting counter-play. It would go sideways if that champion flashed over a wall, thus pulling their team to safety. :P But as you said, only when the ult is reactivated do they pull together.
b) I would not chose having them pull to Emily herself. That would be stupid overpowered.
c) To a chosed location with a range from the first enemy champion hit? So you cast R, then select a location, thus reactivating the ult, making the champions pull together. This doesn't work in my mind either because what is making them go to that location??? It doesn't make sense. It could be balanced, but it would be a BIG stretch.
d) Make them pull to the middle enemy champion hit? No, now I'm just reaching for ideas. This isn't a good idea imo either.
4) She has about as many CC abilities as Leona. Meaning, she is probably going to have some crazy long cooldowns for her W, E, and especially her ult. Just keep that in mind.
But again, AWESOME concept art and ability concepts!!!!! I'm going to keep an eye on this to see where this goes!!!