If you find IO while Luna is still active, instead of targeting Luna to get her down go for IO. When she dies, her fox dies. This is similar to Barik with his deployable and Inara with warder's field. They all are removed from the field after death
Watch out for his ability to leave behind an explosive fissure, and stay away from it! This would result in him getting healed and you taking severe damage. Make sure to track him too, so as soon as he is physical you can attack and kill him.
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!
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!