Ying is able to teleport to her allies during her ult, so when she does try to kill her on sight. She can still have her ult going after she dies, but it can make it harder for the enemy to be healed. Also, remember she can teleport multiple times!
Dimensional Link can also let her travel to the last active illusion spot after it dies, and this can help her escape combat quickly, especially if she has an illusion hidden to heal her team. She is only able to have 2 active, so know their spots!