Dissonance

Dissonance is a purple mist shown in specific rooms throughout Eg-Lana, referring to places where children of the same seed are in conflict. All six pieces of dissonance must be absorbed by Beherit to seal the Corridor of Blood and complete the game.

Valhalla
Located in Vritra's room (E-2) after defeating it.

Dark Star Lord's Mausoleum
Located in Aten-Ra's room (C-8) after defeating him.

Heaven's Labyrinth
Located in Typhon Room (C-4). After beating Echidna, Guardian of the Hall of Malice, speaking to Typhon should present three options, the third of which is a shut-down option. Shut down Typhon and absorb its dissonance.

Mausoleum of the Giants
Located in E-4. You must complete the Sakit's Grave puzzle in Eternal Prison - Gloom.

Nibiru
Use all 12 crystal skulls on the skeletons around the area, then stand on top of the master skull in the top room and use a fully charged Mjolnir to charge the gates (note: you can charge Mjolnir in Nibiru by being hit by the turrets in the side chambers).

Eternal Prison - Doom
Located in Hel's room (A-3) after defeating her.

Activating the Spiral of Life
After getting all 6 Dissonance, use the Beherit in front of all of the Corridor of Blood doors until they shoot out a red laser. Follow the path for all 6 of them and they should activate the Spiral of Life on the Spiral Boat at Immortal Battlefield (E-4). It is advisable to complete the Glossary ROMs and Brahma's Trials as they can become inaccessible after doing this, in addition to anything else you may want to do!

The next thing you'll want to do is fight Heimdall at Annwfn (C-5). Chant Nótt in the room to begin the fight.

Afterward, you will want to get to the Spiral Boat and open the Spiral Boat door.