Typhon Ragnarok (damage numbers normalized to unmitigated using my Damage Calculator)
Normal attack: ~3000 damage
Special attack: Removes all debuffs on self
Normal Overdrive: ~6000 damage to entire party, self ATK buff
Raging Overdrive: ~8000 (?) damage to entire party
Recommended souls: Andromeda (rapid healing) and Jeanne (damage mitigation).
Constant debuff removal means debuffs won't be very effective. You'll want defense debuffs on hand to buff your Burst, however. The normal overdrive is dangerous, so you'll probably want to use Jeanne to mitigate it. That'll also be the time to use any ATK down debuffs you have.