Gorgyra

Gorgyra is an Undying Cie'th, originally a Guardian of Paddra Nsu-Yeul before she transformed and is a sidequest target in Final Fantasy XIII-2. Defeating her grants the party a Gorgyra shard, which gives 500 CP.

Datalog
''Best of the Bestiary There was once a female warrior of Paddra, bound to serve the goddess, who was tricked by an enemy and almost caused the seeress to be killed. Now, the seeress loved the warrior like a sister, and she forgave the mistake. But the warrior did not, and as penance she asked the fal'Cie to turn her into a Cie'th. When the warrior finished her prayer to the fal'Cie, an ominous voice rang through her head. 'I have heard your plea. You shall lose your five senses, be plunged into black flames, and wander the eternal darkness. Your words shall be a song of agony; your screams a curse of death. And thus shall you remain, until a merciful one destroys your soul and frees you from your torment.'''

Strategy
Before even attempting the battle with Gorgyra, which you will not be able to do when you first reach Yaschas Massif -01X AF-, you should have a party decently leveled to about 3,000 HP for Noel and 2,500 HP for Serah. It's also a good idea to equip accessories that provide some immunities to ailments. Fog is the #1 priority here, as you'll be virtually useless if you can't keep up on removing status.

The Diversity paradigm (COM-RAV-MED) is almost a necessity, as you'll need to be constantly healing your party and casting Esuna to deal with the countless waves of harm Gorgyra sends your way. Since Gorgyra can have some ailments of his own inflicted, such as Deprotect and Deshell, a paradigm with Saboteur in it would be a good route to take in lieu of Gorgyra's whopping HP stat of 848,000. Aside from that, staple paradigms like Aggression, Relentless Assault, or Tri-Disaster are good to take at certain points in the battle when staggering, and especially for a late push.

Time is your enemy in this battle, so you want to focus on being able to stagger. If you find yourself losing your stagger because you keep switching to recover status ailments, you need to sit back and rethink your strategy. If the battle lasts too long, Gorgyra will cast Doom on your party, ensuring your demise if you don't pick up the pace. Some recommended Monsters to use in your paradigms are Cloudburst or Circuitron. Both are capable of using the Friendly Fire Feral Link ability, which with cast both Faith and Enfrost or Enthunder on your entire party, exploiting Gorgyra's weaknesses to the fullest.