Please see https://www.wowhead.com/guides/dausegne-the-fallen-oracle-encounter-journal-boss-abilities-raid-loot for full information.

Brief Tactics:

• Start at centre of room.

• Dominion Core add needs to be picked up, interrupted and cleaved down asap.

• Add spawns swirlies that leaves black puddles - DON'T STAND IN THEM!

• Staggering Barrage - one player marked with arrow and line - other players stand on line to split damage.

• Boss does dark cone - avoid that.

• Tanks taunt swap as debuff drops off.

• At zero mana, boss teleports, shields, does raid wide damage and increases puddle sizes.  Raid stack and nuke shield.

• Disintegration Halo rings spawn from reservoirs at edge of platform.  1 at start then additional one after every shield break.

• First ring will do small amount of damage but give a debuff that will one-shot you if you pass through another ring with it on.

• See where ring is going to spawn from and stack near it, see where next one is coming from and go to furthest point away, to allow debuff to drop before being hit, etc.