This is the Light Egg boss who has several tough attacks, and it has 2 forms.
1st form I beat on lv27 Dragon main char, some A+B gears.
Most useful weapon is King Boar Sword with +12% HP get back on physical attack. Keeps your hero going
Party had Fushimara old guy with white hair and hercules shadow for lots of HP
and a healer any with Minotaur shadow.
2nd form is nasty, if you stay away it HP drains you, meteors you, in close it shines you and reflects phys damage
Also near end it soul lance attacks you which is an instant kill, so dodge roll out from THAT 1 (!!)
Before fighting it buff up on skills - yoga, MP recover, guard all and ATK up all
Weigh into it, when it reflects phys dmg back off and buff again party, heala, yoga, etc
Then go back to phys attack, block when it HP drains you, dodge roll meteor and shine, keep phys attacking it.
Took me 3 tries but I beat it
For 2nd form I was lv32 Dragon with all A gear, fully levelled, also party had A levelled up as well