Sire Denathrius

General Strat

The first phase is all about managing your Burden of Sin stacks. You start the fight with 5 stacks and need to end the phase with low or no stacks. You lose a stack every time you stand in front of the boss for his Cleansing Pain frontal cone and spawn an Echo of Sin add.
The boss will cast Blood Price occasionally. This will stun several players then deal damage to everyone who has the same # of Burden of Sin stacks as them. If its possible to do half the raid on cycles of 2, everyone will be low stacks going into p2. Odds - Evens - Odds - Evens - cont.
Denathrius will spawn several Night Hunters that will focus on several players. After 6s, They will charge to those players and less damage for every player they charge through. Soak these but only be in one beam. Make sure to not stand on the players targeted, just be in line with them and their Night Hunter.
Denathrius’ sword Remornia will spawn when the boss reaches 100 energy. It will cast Ravage from mid in a large arc that drops a puddle. Bait then move on to the next section.

Denathrius drags everyone to mid then knocks them to the edge of the arena. Players who still have Burden of Sin stacks from phase 1 are silenced, take 900% more damage, and lose 20% movespeed per stack. Running within 15 yards of the boss removes your Burden of Sin. If you fail to remove your stacks in 15s, you die.

Throughout phase 2, Crimson Cabalists will spawn. These adds all must be dead by the time the boss reaches 40% health. They do raid damage and shoot out anima when they die, similar to N'zoth adds.
The tanks will face Denathrius towards the Crimson Cabalists and hit them with his Wracking Pain frontal to make them take 50% more damage so don’t get caught in it.
Denathrius’ sword Remornia will be attackable and share damage taken with the boss.
Remornia Impales random players, dealing damage to anyone that gets caught in the way then dropping a puddle. Bait these Impales away from the raid.
When Denathrius reaches 100 Energy Remornia will cast Massacre, hitting anyone near it then dropping a puddle.
Denathrius casts Hand of Destruction, pulling everyone into him then leaving an image that will explode 6s later. Treat these like Soul Flay on Xanesh and run away. We may also use the mirrors to teleport to the other side of the room.

The room will be surrounded with Indignation. This disables the mirrors and forces the raid to only use the center of the platform.
Denathrius will target several players with Fatal Finesse. After 5s, he will hit those players and anyone within 9 yards of them then drop a Smoldering Ire orb. These orbs need to be stood on and soaked before they explode.
At the end of Denathrius’ Shattering Pain attack on the tank, everyone will be knocked back. Avoid having your back to anything dangerous during the cast.
At 100 Energy, Denathrius will spawn a Sinister Reflection that will Ravage players in a frontal arc and Massacre players near them. Both of these abilities drop puddles. This may be a case of drop adds -> move -> drop adds -> move. It also may just be that they follow players and cast these.