That's so heartbreaking...I just wish there was something to do to save it, or even a very clear answer as to what was the cause. My 2 hammers on the other side of the tank are absolutely thriving, even at this very moment, so I'm just really confused as to why this took such a bad turn.As someone who is passionate about torches and euphyllia in general (entire tank dedicated to them, with more than 24+ torches and 24+ other euphyllia), there are times when there is nothing we can do to stop the progression that you are experiencing. I've had aussies for 3-4 months up and completely die for no reason, when all the other euphyllia are doing great.
Dipping excessively is only adding insult to injury... I've also realized that putting torches in a DT is a gamble. My fish have destroyed everyone I put in... no not eating, just constantly rubbing up on them and irritating them to complete failure.
Stable parameters (as vetteguy and merkey noted), consistent low flow, consistent low-mod lighting is the key to success. Even then, it's a crap shoot at best.
My best guess is that there is something in the water they came from (bacteria or algae) that we just don't have in our tanks, and that's leading to the loss.
From the first pic, it's clear that there is tissue recession on the skeleton. Once that happens, you may as well consider it done...
Just my 2 cents...