The circular attack is called Weight of the Land. It doesn't knock you off the edge, but will deal HEAVY damage or one-shot you. Sadly there's no way to dodge this unless you memorize his attack rotation and start moving the instant the AoE marker appears on the floor. The cast time is too fast to dodge*based on human reaction time so memorization is key. Always be mindful of your party mates locations as well, as you don't want to run into their AoEs by accident while dodging your own.

The pillar-shaped AoE that knocks you off is Landslide. It has a much longer cast time so just sidestep out of it when you see it appear on the ground.