Insula Ventorum 20,000 B.C.
|Overcoming the Insula Ventorum 20,000 B.C.||Beat the Insula Ventorum 20,000 B.C.||x100|
Corinda Plains - Top Left Ivy Vine - Bottom Left 
Skills: Insula Ventorum 20,000 B.C. (Hidden Boss)
|Starts battle with Wind King Stance|
|HP stopper at 50% HP and Deploys Wind King Stance|
|-||Dynamo||Preemptive stun on all enemies + Deploy Wind King Stance|
|-||Galactic Wind||Wind type magic attack on all enemies|
|-||Beta Decay||Fixed 3000 damage on all enemies|
|-||Accretion Disk||Remove all ailments, buffs and debuffs on self + self physical and type RES Up L (2 turns)|
|-||Twin Quasar||Push 2 random opponents to reserve|
|-||Stellar Wind||Random wind slash attack x3 + inflict 2000 damage Pain|
How to find Insula Ventorum 20,000 B.C.
To unlock this battle, you will need the "Spirit Detector". This can be found in Spirit Sanctuary after completing the Zerberiya: Sword and Wings Mythos: Song of Sword and Wings of Lost Paradise Mythos, chapter 8. Go back to the boss room and check the hidden room on the far right (now accessible due to collapsing pillar).
Insula Ventorum 20,000 B.C. itself can be found in its own area in Corinda Plains. Once you have the Spirit Detector, you can take the upper right path, climbing the vines to the plateau, then the area will unlock in the lower left section.