[Eru]

Yep, scale's an Ophidian drop. I think they're in the second stage as you get close to the end, but you have to backtrack down a path to get to them. There's just one little cluster of them. Keep an eye out for a giant serpent statue.

Ah, and if it's an ophidian body type, that is all you need, they don't have to be named "Ophidian."

The scale only drops from "Damballah" though, a rare spawn in that group.