@riot: instead of mobility, why doesnt leblanc play around an ability like tricksters glass?
http://comicsidontunderstand.com/wordpress/wp-content/uploads/2008/04/bothofyou.gif
i guess back when the champion was designed, the best definition of a "deceiver" riot could come up with in terms of gameplay was a champion who could pull off some sick jukes with lots of mobility, or make an enemy chase after a clone instead of himself.
whats wrong with her current kit?
well, mobility on a ranged, bursty assassin creates its own problems as we have seen over the years with both
and 
the main issue with these champions is, that their playstile revolves around exceptionally low risk assassinations. due to their high threat range and extra distance they get between them and their opponents.
both kassadin, and leblanc when strong require very low levels of commitment that is usually expected of assassins to burst an opponent down.
on the flip side their exceptional mobility makes them very safe when it comes to catching them out in an undesirable spot themselves.
time for a kit rework.
i think instead of revolving around mobility as her tool of deception, her w should be replaced with an ability like tricksters glass. for everyone who hasnt been present during the whole blackmarket brawlers event, this is what the item did:
Unique – Disguise: Teleports to the target allied champion (550 range) and takes on their appearance for 30 seconds. The disguise includes the target's current health, mana and emotes. The disguise is broken upon casting a spell or attacking, or upon your or the disguise's health being dropped to 0. 90 second cooldown.
how would this ability be realized in the actual game?
- i think leblanc should somehow be able to target any allied or enemy champion to take on his appearance
- the enemy team gets notified which champion was copied via an indicator, but can not distinguish who is who
- otherwise the ability would work just like in the description of tricksters glasses mentioned. the illusion would get broken the moment she deals damage to any target in any form
she would play around deceiving her target and get into range for an assassination by either luring it into a false sense of security, or by baiting him into fights.
for example imagine an adc and a support playing on bot lane, and watching their jungler come in for a gank, commiting into a fight. but oh no! it was leblanc the entire time, and now theyre actually the ones getting caught.
or imagine leblanc copies the look of her own squishy support on very low health. the enemy thinking he has an easy target in front of him gets baited into the burst chain of the leblanc.
the possibilities are endless.
why this ability in particular?
well, its actually part of her lore. for those who remember the journal of justice, she pulled this thing on jarvan, when she went full emperor palpatine and started a war between demacia and noxus while controlling both sides.
it would actually make a lot of sense for her in particular to be able to mirror the looks of other champions.
ult if she could transform into enemies.