The Dungeon Journal of the 11.1 PTR may indicate a secret phase on Mythic Gallywix, the final boss of the Liberation for Undermine raid!
Chrome King Gallywix Dungeon Journal
The Chrome King Gallywix encounter dungeon journal looks like a typical last boss fight with 3 phases and 1 intermission phase according to the in game Dungeon Journal. Check out the dungeon journal below for Normal and Heroic.
