I've done it once. The one that I'm using in Arena right now is my 500k HP 340 Power Warrior.
By the time I got 350k HP with 1700 Power, Im using 3 Eternals. CV Necklace, Aethereal Drain MH, Satyr's Spirit Eternal Pet w/ 15000 MP. MP Based Set using BloodMagic.
But now I don't have it anymore because when I change my phone I forgot to save my data and lost my Eternal Pet.
If you wanna look my present character, go I'm just using Warrior right now with 500k+ HP and 340 Power. I maximized the HP to 700k last time but seriously sucks.