I think I found 2 issues with the Lost Naga, one of which I'm not sure I can do anymore possibly because one bug is blocking the other?
First, in an earlier version I found that you can purge Silas' Curse after defeating the Naga. I was able to repeatedly purge the curse again and again (without repeating the fight. It would just let me keep pressing it) which would cause me to grow exponentially. Second, it seems that every time you defeat him after you obtain his special move, he keeps offering to give you the powered up version of the ability again and again which doesn't seem to do anything. Due to the second issue I can't seem to purge the curse anymore.