These suggestions are coming from me experiences with Ying.
First thing to do should be removing "Life Exchange" talent. Instead of that making "Shatter" targetable.
How should this work :
-If target is allied illusions heal the target for 800 but don't explode.
-if target is an enemy illusions charge to target and explode dealing 500 damage.
-if no target selected illusions explode and healing allies around them for 500. Also deals damage if Ying is using "Resonance" talent. (duh!)
Right now illusions are pretty dumb. They stuck at corners, they charge at wrong target. With this change those problems will be solved and illusions become more usefull. Also shuts the people who yelling at Ying players for not picking "Life Exchange".
Second thing to do is, new talent. (since we removed one)
Relativity: Whenever Ying teleports with "Dimensional Link" she deals 400 aoe damage both at the cast location and target location.
Ying can use that both defensive and offensive. I think it will be usefull against close range attackers.
Last one: Right now Ying can't protect herself against long range heavy hitters like snipers and Dragoz. All she can do is hide under a rock and spam illusions from there. To change that, "Focusing Lense" should remove damage fall off. So Ying can return fire and defend herself. (In the upcoming patch they are reducing damage fall off but i am not sure if that will be enough.)