Which song was played in Naruto Shippuden episode 378 at about 15:10, when Obito attacked Naruto and Sasuke?
I recognize this track from the Madara vs the Shinobi Alliance fight.
It looks like this one wasn't released in any of the official OST soundtracks. It doesn't appear in any of the tracks in this list (as of 2018).
There are some unofficial versions online, although they are low quality because of the limited sample size. For example, there's one here, titled "Fighting Akatsuki" by the uploader.
I think that is a clip taken out of "Shouryuu" or "Rising Dragon" starting at about 0:30 into the OST.
It is from Naruto Shippuden OST 2 and is Track 1.
Source: Naruto Music on Wikia