When he's 10% hp, Tears casts a celestial on herself, and all incoming damage is blocked. To remove celestial, we need to use water dragon scales, all party, at the same time.
We tried this 2 times, and everything was perfect, but celestial wasn't removed.
Is it bugged or something? Maybe this is why hellbound isn't open after all this time?
Make duo party and remove it with 2 people only.
don't use pets when u're removing celes