This matchup is extremely difficult, but try to make her waste her fire by going planted, then immediately switching to travel form. (note that you will still take much damage but it won't be an insta kill)
Corvus stun is great counter to khan, as it passes through his shield and leaves him vulnerable for the kill. He's also an easy target to hit your knife.
As Yagorath, you are a prime target for Ruckus to use his Hexa Fire on you, if you suspect he is going to use it soon try to preserve Harden and use it when he activates it to massively reduce the high Damage it deals.
Yagorath is perfect for massive shock pulse chains, she is easy to hit during her planted form and the shock pulse will chain into her team and deal good damage.