I'm not sure if this is intended but if you defeat the first two NPCS and go back into Mt Pyre to heal you will have to fight the two NPCS again, this might go for the rest of the NPCS on the exterior but I only tested it on the first two. Again, I'm not sure if this is on purpose but I tested it twice so I'm pretty sure its reproducible.
The first magma member will be visible and the 2nd one is invisible, iirc the first time I came through they were both visible