Siman 242

(2.) Regarding the matter of his ability to make an appeal [andasenye] and send the matter to the Emperor himself etc. [Likutay Moharan, Torah 175]. And he said then: "What you see — that sometimes I write something and burn it — I send the matter through the smoke. And Rabbi Shimon bar Yochai alluded a little of this in the holy Zohar etc."