Killed it in about ~30 Minutes with 4 people, Never really in danger at any time, even forgot to bring Stona =( but Break-ga only laster about 30 Seconds, not even long enough to break my White HP.
RDM/SMN/PLD/BLU was our set up, I tanked on PLD with full MDT/MDB Gear (-25%MDT, +20MDB roughly, gimp set really =x, no HQ's anywhere), BLU and SMN did the majority of the Damage, RDM kept me alive and the mob DoT'd Debuffed.
As HP got lower its Stoneskin (seemed) to become more powerful, this is reported so likely just backing that up, but Regurgitation was doing ~550DMG Consistently and Garuda was doing ~600.
Fun fight over-all, like a dumbed-down Ouryu, Much weaker, Able to be Stunned and Slowed as well.