LeBlanc Ultimate Idea
First off, .. I have no insight on if or when LeBlanc will enter this game. This is purely theoretical.
I think this would be a good ultimate ability for her, or possibly for some other champion that this could rationally fit for.
As for the idea
When she casts her ultimate, she briefly goes invisible (this drops targeting), she immediately returns along with a clone at an adjacent space. This clone will remain for 3 seconds. It can take damage as normal (starting with the same health as LeBlanc when she cast her ultimate), and if it drops to 0 health before the 3 seconds are up it disappears. It does attack enemy champions but deals no damage (does not apply effects) and does not accumulate mana for the real LeBlanc.
Basically, .. This clone could POTENTIALLY absorb damage and abilities if the enemy AI targets it instead of the real LeBlanc or another allied champion.
Personally, i think this could be enough, .. however, I do understand that LeBlanc is a damage dealing champion, so most likely people would want her ultimate to deal damage. In order to incorporate this, I would incorporate the Distortion ability into her ultimate so that summoning the clone looks similar to Distortion and make it summon more than one space away from the original (have the game randomly decide if the clone remains where it started or if it blinks to the new location, leaving the clone in the original location) and have both clone and real LeBlanc deal damage to all adjacent enemies.
This was just a quick idea. I honestly hadn't put any thought into origin, class, items, synergies, health, mana, ...
I would be perfectly fine with someone taking this idea and using / modifying it to put together a more complete concept.
Also, feel free to share your ideas with me.