User blog comment:Joe021093/Emerald-Mercury vs Coco-Yatsuhashi Battle Review/@comment-4909254-20151130035252/@comment-2166962-20151201173246

I'm sorry if I wasn't clear, but the fog I meant was from when the ammunitions Mercury made hit the ground. It's like he's throwing some sort of gas/fog bomb-- that's what I meant.

And the spinning is indeed his semblance or work of Dust, I think.