(For Treacherous Ground vs Firing Line). When you want to Ulti, try dropping Warder's Field first, to try and bait Khan into using his Shout. Once he's used it, wait 4-5 seconds, and then Ulti once the CC immunity has worn off.
If you see a khan going Commanders grab, switch to Treacherous ground (Warder's field) because when you place it down he wont be able to grab you, and if he uses it to get into point, as long as youre in Warder's field he will be stopped.
Be very careful of Khan ult, as if Inara gets thrown off the map, she has no way to save herself. You can use the Mother's Grace talent to give him fewer chances to attempt to grab you, otherwise play carefully with lines of sight.