How are you doing phase 2? Are you killing 1 wave of adds then just burning deathwing? Or is it the first terrors that spawn that kill you before the ranged kills them? I would recommend focus firing the terrors if that's the case.
What I would do is:
Land on platform, DPS Deatwhing until the adds spawn.
Kill all adds and terrors
Back on Deathwing, controlled DPS down to 11% and STOP don't hit 10% because it will increase corrupted blood damage. Wait for a new add wave to spawn, and kill everything. Once the Terrors are dead, hit bloodlust and just burn deathwing, ignore any adds that spawn unless terrors spawn then you just pick them up and use every cooldown and trick in the book to stay alive until deathwing dies.
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