Just hope that you can escape because grover can't out damage skye so hope that they are a bad skye and miss or your dead if you don't escape.

Just get up close and circle him while you aim at his head. Raum is slowed alot while shooting.

If she ults hide behind something big enough to cover your whole champion. This way you can dogde all the damage and have it explode on the other side of the wall.