Maeve is probably the safest pick against Raum, cause its hard for him to hit you. He also has high damage-falloff, you don't, so you can use that to your advantage and keep your distance.
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.
Terminus siphon annoying you? You can ult him, which gets rid of his siphon and have your team burst him from there. Your gourd is on the ground, which damages him even if he has his siphon up.