Stonescale Passage

Eidolon of Earth summons Dark Vortexes and Eidolon of Air creates Lightning Orbs that follow a designated target. The vortex and orb will each count as a stack of Divergence. Too many stacks will put you at risk of instant death. Once the Eidolons have switched positions at the 60% HP threshold, bait the Lightning Orbs into the Dark Vortexes to reduce the number of Divergence stacks.

While the warrioress Amasa remains out in the open to battle a ranged opponent, Amayun bolsters his defenses, summons the Karmic Mirrors around the arena, and enters Spatial Isolation with a melee opponent. Let the melee target trick Amayun and have him bait Sword Schism beam-attacks onto the Karmic Mirrors to open a path between the real world and Spatial Isolation. As soon as Amasa focuses her attention on a target with her Snake Eyes, be quick to enter Spatial Isolation and remove Amayun's defense stacks. Before moving into the final phase, block the energy beams sent from Karmic Mirrors from reaching Amasa and Amayun.

Finally, the bosses will both unleash Stone Schism and Sword Schism attacks. With the paths through the Karmic Mirrors remaining open, bait the attacks through to turn Amayun into stone.