Akali idea, making her current w her ult instead.
http://2.bp.blogspot.com/-EIjAHKWjDnw/VQKIkK6ckNI/AAAAAAAAmEU/Afear6JgMkA/s1600/w.jpg We all know that Riot plans on reworking/updating Akali in the near future. It's possible that she is already done and is in waiting for the assassin rework this winter. However, i couldn't get this idea out of my head of Akali's W becoming her ultimate. When i Imagine a ninja with a smoke screen, i imagine a fast image darting around its target like a shark in the water. to the prey, it would look like shadows in the corners of your eye, or catching brief moments of the attacking ninja.
That's when I had the Idea of Akali's Smoke screen Ult. This ultimate would be large, about the size of trundle's W. Inside this zone Akali would be completely invisible, even to stealth wards, unless she was attacking her target. If she was attacking her target, only her target would see her, but her allies will see their ally in distress. This would be similar to the velociraptors from the Jurassic park 2. She would also show up after so many seconds as an after image similar to the sweeping lens trinket when detecting stealthed champions.
https://www.youtube.com/watch?v=Cr1MvzAr26E
Now, for an ultimate like this, she would need buffs while in the zone like her current brief movement speed that she gets in her current W.
I don't have any other ideas that would work with this, but it would be really cool to have a zone like assassin, and having a ninja living up to its theme. 
. If any invisibility champ could use that, it's her, but I can think of a number of champs with invisibility that would be calling bull that she can be invisible no matter what while their invisibility is practically countered as soon as someone places a
.