Board Thread:Theories and Speculation/@comment-26889573-20151008053113/@comment-1872728-20151011192249

That's actually just an advanced version of fire release. All Sasuke does is apply a shape transformation to the Amaterasu ^_^ I think that it's not an advanced version of Fire Release, since it's inextinguishable. I think that's it's actually Fire generated with Six Paths Chakra, or something similar to it, since Sharingan is a diluted version of the Rinnegan, so it has the diluted version of the Six Paths Chakra. Like how Sasuke's Chidori turned black when utilising Six Paths Chakra.